The Nature of Flavor and Flavorings

Flavor Is Part Taste, Mostly Smell

The Evolving World of Taste and Smell

Flavorings Are Chemical Weapons

Turning Weapons into Pleasures: Just Add Food

The Chemistry and Qualities of Herbs and Spices

Most Flavorings Resemble Oils

The Flavor of an Herb or Spice Is Several Flavors Combined

Flavor Families: The Terpenes

Flavor Families: The Phenolics

Flavor Families: Pungent Chemicals

Why Pain Can Be Pleasurable

Herbs, Spices, and Health

Handling and Storing Herbs and Spices

Preserving Aroma Compounds

Storing Fresh Herbs

Drying Fresh Herbs

Cooking with Herbs and Spices

Flavor Extraction

Marinades and Rubs

Herbs and Spices as Coatings

Extracts: Flavored Oils, Vinegars, Alcohols

Flavor Evolution

Herbs and Spices as Thickeners

A Survey of Common Herbs

The Mint Family

The Carrot Family

The Laurel Family

Other Common Herbs

A Survey of Temperate-Climate Spices

The Carrot Family

The Cabbage Family: Pungent Mustards, Horseradish, Wasabi

The Bean Family: Licorice and Fenugreek

Chillis

Other Temperate-Climate Spices

A Survey of Tropical Spices

Tea and Coffee

Caffeine

Tea, Coffee, and Health

Water for Making Tea and Coffee

Tea

Coffee

Wood Smoke and Charred Wood

The Chemistry of Burning Wood

Liquid Smoke

Herbs and spices are ingredients that we use to add flavor to foods and drinks. Herbs are plant leaves, fresh or dried, and spices are bits of dry seed, bark, and root. We consume them in tiny amounts, and they have practically no nutritional value. Yet from earliest times, these aromatic bits have been among the most highly prized and costly of all ingredients. In the ancient world they were more than mere foods: they were thought to have medicinal and even transcendental properties. Sacrificial fires wafted the fumes of aromatics upward to please the gods, and at the same time offered earth-bound humans a whiff of heaven. Spices came from the ends of the earth, from Arabia and legendary lands to the east. The growing hunger for the aromas of paradise helped drive the European exploration of the globe, the discovery of the Americas, and the biological and cultural exchange that helped shape the modern world.

Few people today think of herbs and spices as emissaries from paradise or to heaven. Yet they’re more popular than ever: because herbs and spices do indeed bring other worlds to our table. They mark the foods of different cultures with distinctive flavors, and provide us a taste of Morocco at one meal and Thailand the next. They help us recapture the kind of sensory variety that our ancestors enjoyed in foods before agriculture made eating both more reliable and more monotonous. And because smell is one of the senses through which we experience our immediate surroundings, herbs and spices delight by lending our foods hints reminiscent of the forest, the meadow, the flower garden, the seacoast. They can conjure a familiar part of the natural world in a bite or sip.

This chapter surveys herbs, spices, and three other important flavorings derived from plants. Tea and coffee are such prominent ingredients in their own right that we don’t think of them as herb or spice, but that’s essentially what they are: tea is a dried leaf and coffee a roasted seed, and we use them to flavor water (and infuse it with a useful drug, caffeine). And wood smoke is a flavoring created when intense heat breaks plant tissues down into some of the same aromatics found in true spices.

The Nature of Flavor
and Flavorings

Flavor is Part Taste,
Mostly Smell

The function of herbs and spices is to add flavor to our foods. Flavor is a composite quality, a combination of sensations from the taste buds in our mouth and the odor receptors in the upper reaches of our nose. And these sensations are chemical in nature: we taste tastes and smell odors when our receptors are triggered by specific chemicals in foods. There are only a handful of different tastes — sweet, sour, salty, bitter, and savory or umami (p. 342), while there are many thousands of different odors. It’s odor molecules that make an apple “taste” like an apple, not like a pear or radish. If our nose is blocked by a cold or pinching fingers, it’s hard to tell the difference between an apple and a pear. So most of what we experience as flavor is odor, or aroma. Herbs and spices heighten flavor by adding their characteristic aroma molecules. (The exceptions to this rule are the pungent spices and herbs, which stimulate and irritate nerves in the mouth; seep. 394.)

Odors and the Suggestiveness of Volatility The aroma chemicals of herbs and spices are volatile: that is, they’re small and light enough to evaporate from their source and fly through the air, which allows them to rise with our breath into the nose, where we can detect them. High temperatures make volatile chemicals more volatile, so heating herbs and spices liberates more of their aroma molecules and fills the air with their odor. Unlike most of the objects that we sense around us, which we see or touch or hear, aromas are an invisible, intangible presence. To cultures that knew nothing of molecules and odor receptors, this ethereal, penetrating quality suggested a realm of invisible beings and powers. So herbs and spices became important in the sacrificial fires and incense of religious ceremonies; they were offerings to the gods, a way of evoking their presence and imagining their heaven. Perfumes — a word that comes from the Latin for “through fire” — have long been the source of a similarly mysterious appeal.

The Evolving World of Taste and Smell

We humans are animals, and for all animals, the sense of smell does far more than provide information about a mouthful of food. Smell detects whatever volatile molecules are in the air. It therefore tells an animal about its surroundings: the air, the ground, the plants growing in the ground, other animals moving nearby that might be enemies, mates, or a meal. This more general role explains why we’re sensitive to aroma notes in foods that are reminiscent of the world: wood, stone, soil, air, animals, flowers, dry grass, the seacoast and the forest. It’s also essential for animals to learn from experience, and therefore to associate particular sensations with the situations they accompany. This may be why odors are so evocative of memories and the emotions associated with them.

The Variety of Gathered Foods, the Monotony of Agriculture Our earliest human ancestors were omnivores: they ate whatever they could find worth eating on the African savanna, from meat scraps on an animal carcass to nuts, fruits, leaves, and tubers. They relied on taste and smell to judge whether a new object was edible — sweetness meant nourishing sugars, bitterness toxic alkaloids, foulness dangerous decay — and to help identify and recall the effects of objects they had encountered before. And they ate a varied diet that probably included several hundred different kinds of foods. They had a lot of flavors to keep track of.

When humans developed agriculture around 10,000 years ago, they traded their diverse but chancy diet for a more predictable and monotonous one. Now they lived largely on wheat, barley, rice, and corn, all concentrated sources of energy and protein, and all relatively bland. They had very few flavors to keep track of. But they still had their senses of taste and smell.

Flavorings Provide Stimulation and Play One distinctly human characteristic is a drive to explore and manipulate the world of natural materials around us, to change those materials to suit our needs and interests. And these needs and interests include the stimulation of our senses, the creation of sensory patterns that engage our brains. After the development of agriculture and its radically simplified diet, our ancestors found ways to give our taste buds and nose more to experience again. One way was to make use of plant parts that are especially concentrated sources of flavor. Herbs and spices made it possible not only to give bland foods more flavor, but to give them more varied flavors, to ornament foods and highlight flavor for flavor’s sake.

Flavorings are
Chemical Weapons

And why are some plants’ parts especially potent, intense sources of flavor? What role do the chemicals that give them their flavor play in the lives of the plants themselves?

One simple clue is their very potency. Try the experiment of chewing on an oregano leaf, or a clove, or a vanilla bean. The result is far from pleasurable! When eaten as is, most spices and herbs are acrid, irritating, numbing. And the chemicals responsible for these sensations are actually toxic. The purified essence of oregano and of thyme can be bought from chemical supply companies, and come with bright warning labels: these chemicals damage skin and lungs, so don’t touch or inhale. This is precisely the primary function of these chemicals: to make the plants that produce them obnoxious and therefore resistant to attack by animals or microbes. The flavors of herbs and spices are defensive chemical weapons that are released from plant cells when the plant is chewed on. Their volatility gives them the advantage of counterattacking through the air, not just on direct contact, and of being a warning signal that can train some animals to be deterred by smell alone.

Turning Weapons Into
Pleasures: Just Add Food

And yet humans have come to prize these weapons that are meant to repel us. What makes herbs and spices not only nontoxic and edible but delicious is a simple principle of cooking: dilution. If we bite into an intact leaf of oregano or a peppercorn, the concentrated dose of defensive chemicals overwhelms and irritates our senses; but those same chemicals diffused throughout a dish of other foods — a few milligrams in a pound or two — stimulate without overwhelming. They add favors that our grains and meats don’t have, and make those foods more complex and appealing.

The Chemistry and Qualities
Of Herbs and Spices

Most Flavorings Resemble Oils

The flavorful material in an herb or spice is traditionally called its essential oil. The term reflects an important practical fact: aroma chemicals are more similar to oils and fats than they are to water, and are therefore more soluble in oil than they are in water (p. 797). This is why cooks make prepared flavor extracts by infusing herbs and spices in oil, not water. They do infuse herbs in watery vinegar and in alcohols, but both alcohol and vinegar’s acetic acid are small cousins of fat molecules, and help dissolve more aromatics than plain water could. The defensive aroma chemicals can have disruptive effects on a plant’s own cells as well as on predators, so plants take care to isolate them from their inner workings. Herbs and spices stockpile their aroma chemicals in specialized oil-storage cells, in glands on the surfaces of leaves, or in channels that open up between cells. Some dry spices are as much as 15% essential oil by weight, and many are 5–10%. Fresh and dry herbs generally contain much less, around 1%, fresh herbs because their water content is much higher, and dry herbs because they lose aroma chemicals in the drying process.

The Flavor of an Herb or Spice is
Several Flavors Combined

As we’ve seen many times and in many foods, flavor is a composite quality. A ripe fruit may contain hundreds of different aromatic compounds; and the same goes for a roast. Though we tend to think of a particular herb or spice as having its own distinctive flavor, it too is always a composite of several different aroma compounds. Sometimes one of those compounds predominates and provides the main character — as in cloves, cinnamon, anise, thyme — but often it’s the mixture that creates the character, and that makes a spice well suited to serve as a unifying bridge among several different ingredients. Coriander seed, for example, is simultaneously flowery and lemony; bay leaf combines eucalyptus, clove, pine, and flowery notes. It can be fascinating — and useful — to taste spices analytically, trying to perceive the separate components and how their flavors are built. Terms from perfumery can be helpful: there are “top notes,” perceived right away, ethereal and quick to fade; there are “mid-notes,” the main flavors; and there are “bottom notes,” which are slow to develop and which persist. The charts on pp. 392 and 393 list the prominent aroma components in a selection of herbs and spices. There are two particular chemical families that contribute many of the aroma compounds in herbs and spices.

Flavor Families: The Terpenes

Terpene compounds are constructed from a zigzag building block of five carbon atoms, which turns out to be amazingly versatile and can be combined, twisted, and decorated into tens of thousands of different molecules. Plants usually produce a mixture of defensive terpenes. They are characteristic of the needles and bark of coniferous trees, of citrus fruits (p. 374), and of flowers, and provide pine-like, citrusy, floral, leaf-like, and “fresh” notes to the overall flavor of many herbs and spices. As a family, terpenes tend to be especially volatile and reactive. This means that they’re often the first molecules to reach the nose, and provide the initial impression of these lighter, more ethereal notes. It also means that they’re readily boiled off or modified by even brief cooking, which is why these fresh, light notes disappear. If desired, they can be restored to a cooked dish by adding a new dose of the herb or spice just before serving.

Flavor Families: The Phenolics

Phenolic compounds are constructed from a simple closed ring of six carbon atoms and at least one fragment of a water molecule (an oxygen-hydrogen combination). Single rings can then be modified by adding other atoms to one or more of the carbons, and two or more rings can be linked together to form polyphenolic compounds, including anthocyanin pigments and lignin. Unlike the terpene aromatics, which often have a generic quality to them, the phenolic aromatics are distinctive and define the flavor of such spices as cloves, cinnamon, anise, and vanilla, as well as the herbs thyme and oregano. The pungent components of chillis, black pepper, and ginger are also synthesized from a phenolic base.

Examples of terpene aroma compounds. The black dots show the backbone of carbon atoms. Limonene and menthol are distinctive, while myrcene provides a background note in a number of spices and herbs.

Thanks to the water fragment on the carbon ring, phenolic compounds are somewhat more soluble in water than most terpenes. They tend to be more persistent in foods and in the mouth as we eat and taste.

Examples of phenolic aroma compounds.

Flavor Families: Important Terpenes and Phenolics and Their Aromas

Chemical Compound

Aroma

Terpenes

Pinenes

Pine needles and bark

Limonene, terpinene, citral

Citrus fruits

Geraniol

Roses

Linalool

Lily of the valley

Cineole

Eucalyptus

Menthol and menthone

Peppermint

L-carvone

Spearmint

D-carvone

Caraway

Phenolics

Eugenol

Clove

Cinnamaldehyde

Cinnamon and cassia

Anethole

Anise

Vanillin

Vanilla

Thymol

Thyme

Carvacrol

Oregano

Estragole

Tarragon

The Flavor Components in Common Spices

Flavor Families:
Pungent Chemicals

There is a major exception to the rule that herbs and spices provide aroma. The two most popular spices in the world are chillis and black pepper. They and a handful of other spices — ginger, mustard, horseradish, wasabi — are especially valued for a quality often called hotness, but best called pungency: neither a taste nor a smell, but a general feeling of irritation that verges on pain. Pungency is caused by two general groups of chemicals. One group, the thiocyanates, are formed in mustard plants and their relatives, horseradish and wasabi, when the plant cells are damaged. Most thiocyanates are small, light, water-repelling molecules — a dozen or two atoms — that readily escape from the food into the air in our mouth, and up our nasal passages. In both the mouth and nose they stimulate nerve endings that then send a pain message to the brain. The second group of pungent chemicals, the alkyl-amides, are found preformed in a number of unrelated plants, including the chilli, black pepper, ginger, and Sichuan pepper. These molecules are larger and heavier — 40 or 50 atoms — and therefore less prone to escape the food and get up our nose; they mostly affect the mouth. And their action turns out to be very specific. They bind to particular receptors on certain sensory nerves and essentially cause those nerves to become hypersensitive to ordinary sensations — and thus to register the sensation of irritation or pain. The mustard thiocyanates appear to act in a similar way in the mouth and nose.

Why Pain Can Be Pleasurable

Why should irritating spices be our favorites? Psychologist Paul Rozin has proposed a couple of different explanations. Perhaps spicy foods are the edible equivalent of riding a rollercoaster or jumping into Lake Michigan in January, an example of “constrained risk” that sets off uncomfortable warning signals in the body. But since the situations are not truly dangerous, we can ignore the normal meaning of these sensations and savor the vertigo, shock, and pain for their own sakes. The sensation of pain may also cause the brain to release natural pain-relieving body chemicals that leave a pleasant glow when the burning fades.

Stimulation and Sensitizing We may also enjoy spicy food because irritation adds a new dimension to the experience of eating. Recent research has found that, at least in the case of the pepper and chilli irritants, there’s a lot more to pungency than a simple burn. These compounds induce a temporary inflammation in the mouth, transforming it into an organ that is more “tender,” more sensitive to other sensations. Those heightened sensations include touch, temperature, and the irritating aspects of various other ingredients, including salt, acids, carbonation (which becomes carbonic acid), and alcohol. It’s the pepper that makes Chinese hot and sour soup, which is hot and acidic and salty, into such an intense experience. A few mouthfuls and we become conscious of simply breathing: our mouth becomes so sensitive that exhaling body-temperature air feels like a textured hot bath, inhaling room-temperature air like a refreshingly cool breeze.

Examples of pungent flavor compounds. capsaicin

Strong pungency actually diminishes our sensitivity to true tastes — to sweetness, tartness, saltiness, bitterness — and to aroma, in part because it usurps some of the attention our brains would normally pay to these other sensations. Our sensitivity to pungent flavorings also declines with exposure to it, and that desensitization lasts for 2–4 days. This is part of the reason that regular chilli-eaters can tolerate hotter dishes than people who enjoy pungent food only occasionally.

Herbs, Spices, and Health

Herbs and Spices as General Medicinals The idea that herbs and spices have medicinal value is an ancient one, and grounded in fact: plants are virtuosos of biochemical invention, and have been the original source of many important drugs (aspirin, digitalis, quinine, taxol are just a few). The health effects of plant foods in general are discussed above, p. 253. Herbs and spices, with their specialization in phenolic and terpene compounds, are notable for three broadly helpful tendencies. Phenolic compounds often have antioxidant activity; oregano, bay leaf, dill, rosemary, and turmeric are among the most effective. Antioxidants are useful both in the body, to prevent damage to DNA, cholesterol particles, and other important materials, but also in foods, to slow the deterioration in their flavor. Terpenes don’t prevent oxidation, but they do help reduce the body’s production of DNA-damaging molecules that can cause cancer, and help control the growth of tumors. And some phenolic compounds and terpenes are antiinflammatory agents; they moderate the body’s overreaction to cell damage, which can otherwise contribute to the development of both heart disease and cancer.

We don’t yet know whether the consumption of herbs and spices can significantly reduce the risk of any disease; but it’s a real possibility.

Herbs, Spices, and Food Poisoning It has been suggested that people first began to use herbs and spices, particularly in tropical countries, because their defensive chemicals help control the microbes that cause food poisoning, and thus made food safer to eat. While some — garlic, cinnamon, cloves, oregano, thyme — are fairly effective at killing important disease microbes, most are not. And many, especially black pepper and others that take several days to dry in tropical climates, carry millions of microbes in every pinch, sometimes including E. coli and disease-causing species of Salmonella, Bacillus, and Aspergillus. This is why spices are often fumigated with various chemicals (ethylene or propylene oxide in the United States) or steamed. About 10% of imported spices are irradiated to eradicate microbes.

Handling and Storing
Herbs and Spices

Preserving Aroma Compounds

The aim in handling herbs and spices is to retain their characteristic aroma compounds. The volatility of these compounds means that they readily evaporate, and their reactive nature means that they are likely to be altered if they’re exposed to oxygen and moisture in the air, or to reaction-causing heat or light. To preserve herbs and spices, their tissues must be killed and dried out, so that they don’t rot, but as gently as possible, so that water is removed without removing all the flavor. Then the dried material must be kept in closed containers, in a dark, cool place. As a general rule, herbs and spices keep best in opaque glass containers in the freezer (the container should be warmed to room temperature before opening to prevent moisture in the air from condensing onto cold flavorings). In practice, most cooks keep their flavorings at room temperature. As long as they aren’t regularly exposed to strong light, whole spices keep well for a year, and ground spices for a few months. The fine particles of ground spices have a large surface area and lose their aroma molecules to the air more rapidly, while whole spices retain the aromas within intact cells.

Storing Fresh Herbs

Many herbs are young, delicate stems and leaves, and so more fragile than other produce. Because their stems have been cut, they’re likely to be producing the wound hormone ethylene, which in a closed container will accumulate and trigger general deterioration. Most are best stored in the refrigerator in partly open plastic bags, loosely wrapped in cloth or paper that will absorb moisture and prevent microbes from growing rapidly on wet leaves. Because they come from warm climates, basil and perilla suffer chilling injury in the refrigerator and so are best kept at room temperature, with freshly cut stems immersed in water.

The flavor of many herbs is well preserved by freezing, though the tissues suffer damage from ice crystals and become unattractively dark and limp when thawed. Immersion in oil, which protects the tissue from oxygen, also works for a few weeks, after which much of the flavor has oozed into the oil. Herbs in oil should always be kept in the refrigerator, because the same absence of oxygen that’s good for flavor preservation is also good for the growth of botulism bacteria. The bacteria don’t grow or produce toxins at refrigerator temperatures.

Drying Fresh Herbs

Drying is a process that removes most of the water in an herb, which when fresh may be more than 90% water. The basic dilemma is that many aroma chemicals are more volatile than water, so any process that evaporates most of the water will also evaporate most of the flavor. This is why many dried herbs don’t taste anything like the fresh version, and instead have a generic dried-leaf, hay aroma. There are a few exceptions to this rule, mainly Mediterranean herbs in the mint family that are native to hot, arid areas and have aromatics that persist in drying conditions (oregano, thyme, rosemary, as well as bay laurel from the laurel family). Though sundrying sounds appealing, its high temperatures and strong dose of visible and ultraviolet light mean that it generally removes and alters flavor. Air-drying over the course of a few days in the shade is much preferable. Herbs can be dried in just a few hours in a low oven or a dehydrator, but the higher temperature usually causes greater flavor losses than air-drying. Some commercial herbs are freeze-dried, which often preserves more of the original flavor.

The microwave oven turns out to work fairly well for drying small quantities of herbs, thanks to the selective and rapid effects of its radiation. Microwave energy excites water molecules while leaving non-polar oil molecules relatively unaffected, and it penetrates instantly throughout thin leaves and stems (p. 786). This means that all the water molecules in a batch of herbs reach the boiling point within a few seconds and begin to escape from the leaves, while the structures containing the oil-like flavor compounds (glands and canals, pp. 402 and 407) heat up more gradually and indirectly, via the heat of the water molecules. The herbs dry in a matter of a few minutes, with less drastic flavor losses than result from ordinary oven drying.

Cooking With Herbs
and Spices

Herbs and spices are generally cooked along with other ingredients, and as a relatively minor component of the mixture, 1% or less of the total weight. This section explores the extraction and transformation of flavor in such dishes. But some preparations rely on flavorings to provide more than just flavor (p. 401). And a number of herbs — parsley, sage, basil — are delicious on their own, deep-fried just long enough to become crisp and mellow their flavor.

Flavor Extraction

For herbs and spices to provide us with flavor, cooks must find ways to liberate the flavor chemicals from within their tissue and convey them to our taste and odor receptors. For fragile herbs, this may be as simple as strewing the fresh leaves on the dish, as in Vietnamese soups: the eater liberates the aromas by chewing on the leaves, and enjoys them at their freshest. But if the flavors are to be incorporated into the dish, then the flavor compounds must somehow escape from the herb or spice. The cook may leave the flavoring intact and use liquids and heat to encourage the flavors to seep out gradually, or he may break it into particles — chopping fresh herbs, crumbling dry ones, grinding spices — to expose the flavor molecules directly to the dish. The finer the crumble or grind, the greater the surface area from which flavor molecules can escape, and so the more rapidly the flavor moves from flavoring into dish.

Rapid extraction may or may not be desirable. In a briefly cooked dish, it’s essential. In a long-cooked stew, however, a slower release from coarser particles or whole leaves and seeds may be preferable. In pickles and preserves, whole spices provide flavor without clouding the liquid. Once flavor molecules have been extracted into a preparation, they begin to react with oxygen and with other food molecules, and their original flavor is transformed, however subtly. Larger particles release the original flavors over a longer time. Another way to assure some fresh flavors in a long-cooked dish is to add the herb or spice — either altogether or a supplemental dose — toward the end of cooking, or even after the cooking is done.

Prepared flavor extracts such as vanilla extract are handy because the flavor molecules have already been dissolved in a liquid and immediately permeate the dish. Because cooking will only cause their flavor to evolve or to evaporate, extracts are best added toward the end of a preparation.

Grinding, Crushing, Chopping There are several ways of crushing herbs and spices, and they have different effects on flavor. Grinders, choppers, and mortars all generate heat. The hotter the aroma molecules get, the more volatile they become and the more readily they escape, and the more reactive and changeable they become. The original flavors are best preserved by prechilling both spice and grinder to keep the aromatics as cool as possible. Food processors slice into herbs and introduce a lot of air and therefore aroma-altering oxygen, while a pestle pounding in a mortar crushes herbs and minimizes aeration. Careful chopping with a sharp knife leaves much of the herb structure intact to provide fresh flavor while minimizing cell damage to the cut edges; by contrast, a dull knife crushes rather than cuts, bruises a wide swath of cells, and can result in rapid brown-black discoloration.

One positive effect of oxygen on finely ground spices is manifested in the aging of ground blended spices, which are said to mellow over the course of several days or weeks.

The Influence of Other Ingredients Because aroma chemicals are generally more soluble in oils, fats, and alcohol than in water, the ingredients in the dish will also influence the speed and degree of flavor extraction, as well as the release of flavor during eating. Oils and fats dissolve more aroma molecules than water during cooking, but also hang on to them during eating, so that their flavor appears more gradually and persists longer. Alcohol also extracts aromas more efficiently, but because it too is volatile, it releases them relatively quickly.

Two methods of flavor extraction that take advantage of the volatility of aroma molecules are steaming and smoking. Herbs and spices can be immersed in the steaming water, or can form a bed on which the food sits above the steam; either way, heat drives aroma molecules into the steam, which then condenses onto the cooler surface of the food, and flavors it. If placed on smoldering coals, or onto a heated pan, herbs and spices will emit not only their usual aromatics, but aromatics transformed by the high heat.

Marinades and Rubs

In the case of large solid chunks of meat or fish, it’s easy to get herb and spice flavors onto the food surface, but not so easy to get them inside. Water-and oil-based marinades coat the meat with flavorful liquid, while pastes and dry rubs put the solid aromatics in more direct contact with the meat surface. Because flavors are mainly fat-soluble molecules, and meat is 75% water, flavor molecules can’t move very far inside. A distinctly salty marinade or rub can help somewhat by disrupting the meat tissue (p. 155) and making it easier for some slightly water-soluble aromas to penetrate it. A more efficient method is to use a cooking syringe, and inject small portions of the flavorful liquid into many different parts of the meat interior.

Herbs and Spices
as Coatings

A useful side effect of coating meat and fish with a paste or rub of herbs and spices is that such a coating acts as a protective layer — like the skin on poultry — that insulates the meat itself from the direct high heat of oven or grill. This means that the outer layers of meat end up less overcooked, and so moister. Coarsely cracked spices, coriander in particular, can provide a crunchy counterpoint to the softer insides. The flavor of a spice crust is improved if the coating contains some oil, which essentially causes the crust to fry rather than simply dry out.

Extracts: Flavored Oils,
Vinegars, Alcohols

A special case of flavor extraction is the making of flavor extracts themselves: preparations that serve as instant sources of flavor for other dishes. The most common materials used for extraction are oils, vinegars, sugar syrups (especially for flowers), and alcohols (for example, a neutral vodka for flavoring with citrus peel). The herb and/or spice is usually bruised to damage the cellular structure and make it easier for the liquid to penetrate and aromas to escape. Oils, vinegars, and syrups are often heated before the herb or spice is added to kill bacteria and facilitate their initial penetration into the tissue, then are allowed to cool to avoid changing the flavor. Delicate flowers may require less than an hour to flavor a syrup, while leaves and seeds are usually infused in the extracting liquids for weeks at a cool room temperature. When the extract has reached its desired strength, the liquid is strained off and then stored in a cool, dark place.

Because alcohol, acetic acid, and concentrated sugar all kill bacteria or inhibit their growth, flavored alcohols, vinegars, and syrups pose few safety problems. Oils, however, actually encourage the growth of deadly Clostridium botulinum, whose spores can survive brief boiling and germinate when protected from the air. Most herbs and spices don’t provide enough nutrients for botulism bacteria to grow on, but garlic does. Infused oils are safest when they’re made and stored at refrigerator temperatures, which do slow extraction, but also prevent bacterial growth and slow deterioration.

Commercial Extracts Commercial flavor extracts, unlike kitchen-made extracts, are highly concentrated and are added to foods in tiny quantities, a few drops or a fraction of a spoonful in a whole dish. Vanilla, almond, mint, and anise are common examples. Some extracts and oils are prepared from actual herbs and spices, while others are prepared from one or a few synthetic chemicals that capture the essence of the flavoring, but don’t match it in complexity and mellowness (artificial extracts often taste harsh and off). The advantage of synthetic extracts is their low price.

Flavor Evolution

Once the aroma molecules in herbs and spices are released into a preparation and exposed to other ingredients, the air, and heat, they begin to undergo a host of chemical reactions. Some fraction of the original aroma chemicals becomes altered into a variety of other chemicals, so the initially strong, characteristic notes become more subdued, and the general complexity of the mixture increases. This maturing can be a simple side effect of cooking the flavorings with the other ingredients, but it often constitutes a separate preparation step. When cumin or coriander are toasted on their own, for example, their sugars and amino acids undergo browning reactions and generate savory aroma molecules typical of roasted and toasted foods (pyrazines), thus developing a new layer of flavor that complements the original raw aroma.

Maturing Spice Flavors: The Indian System The use of spices is especially ancient and sophisticated in India and Southeast Asia. Indian cooks have several different ways of maturing spice flavors before their incorporation into a dish.

• The toasting on a hot pan of whole dry spices, typically mustard, cumin, or fenugreek, for a minute or two until the seeds begin to pop, the point at which their inner moisture has vaporized and they are just beginning to brown. Spices cooked in this way are mellowed, but individually; they retain their own identities.
• The frying in oil or ghee of mixed powdered spices, often including turmeric, cumin, and coriander. This step allows the different aroma chemicals to react with each other so that the flavors become more integrated, and is usually followed by the sequential addition of garlic, ginger, onions, and other fresh components of what will become the sauce-like phase of the dish.
• The slow frying of a paste of powdered and fresh spices, with constant stirring until much of the moisture evaporates, the oil separates from the paste, and the spice mixture begins to darken. Mexican cooks treat their pureed chilli mixtures in much the same way. This technique yields its own unique flavors, since dried and fresh ingredients (including active enzymes from the latter) can interact from the beginning, and moisture from the fresh spices prevents the dried spices from being as affected by the heat as they are when fried on their own.
• The brief frying in ghee of whole spices, which are then sprinkled on top of a just-cooked dish as a final garnish.

Indian cooks also aromatize some dishes with a remarkable combination of smoking and spicing called dhungar. They put the dish into a pot along with a hollowed onion or small bowl that contains a live coal, sprinkle the coal with ghee and sometimes spices, and cover the pot tightly to infuse the dish with the fumes.

In sum, herbs and spices are remarkably diverse ingredients in themselves, and are capable of producing a remarkable diversity of effects. Combinations, proportions, particle sizes, the temperature and duration of cooking, all have an influence on the flavor of a dish.

Herbs and Spices as Thickeners

Some herbs and spices are used to provide the substance of a dish as well as its aromatic essence. A puree of fresh herbs, as in the Italian pesto sauce made from basil, is thick because the herb’s own moisture is already bound up with various cell materials. And thanks to the abundance of those cell materials — mainly cell walls and membranes — such purees also do a good job of coating oil droplets and so creating a stable, luxurious emulsion (p. 628). Fresh chillis, which are fruits, produce a watery puree, but one that cooks down to a wonderful smoothness thanks to its abundant cell-wall pectins. Many Mexican sauces are made from a backbone of dried chillis, which are easily rehydrated to produce the same smooth puree; and Hungarian paprikashes are thickened with powdered chillis.

Indian and Southeast Asian dishes often owe their thickness to a combination of dried and fresh spices. Ground coriander absorbs a lot of water thanks to its thick dry husk; ginger, turmeric, and galangal are starchy root-like rhizomes, and their starch dissolves during prolonged simmering to provide a thickening tangle of long molecular chains. Ground dried sassafras leaves, or filé powder, similarly thickens Louisianan gumbo. And fenugreek is remarkable for its high content of a mucilaginous carbohydrate called galactomannan, which is released simply by soaking the ground seeds.

A Survey of Common Herbs

Most of the herbs used in traditional European cooking are members of two plant groups, the mint family and the carrot family. The family members resemble each other to varying degrees, so in this survey I’ve grouped them together. The remaining herbs then follow in mostly alphabetical order.

Fresh herbs are usually harvested from mature plants, often as they’re beginning to flower, when their defensive essential oil content is at its peak. The oil content of Mediterranean herbs is higher on the side of the plant facing the sun. An interesting variation is to harvest them as young sprouts with just a few leaves, when their essential oil content can be very different. Fennel sprouts, for example, contain relatively little anise-like anethole, which dominates the flavor of the mature plant.

The Mint Family

The mint family is a large one, with around 180 genera, and it provides more of our familiar kitchen herbs than any other family. Why such generosity? A fortunate combination of several factors. Members of the mint family dominate the dry, rocky Mediterranean scrublands where few other plants grow, and they cope with their exposed situation with a vigorous chemical defense. Their chemical defenses are located mainly in small glands that project from their leaves, external and therefore expandable storage tanks that can make up as much as 10% of the leaf’s weight. And members of the mint family are both promiscuous chemists and promiscuous breeders: individual species make a broad range of aromatic chemicals, and they readily hybridize with each other. The result is a great variety of plants and aromas.

Basil Basils are a large and fascinating group of herbs. They’re members of the tropical genus Ocimum, which probably originated in Africa, and was domesticated in India. There are around 165 species in the genus Ocimum, several of which are eaten. Basil was known to the Greeks and Romans, took firmest root in Liguria and Provence, inventors of the popular basil purees called pesto and pistou, and was hardly known in the United States until the 1970s. The standard “sweet basil” of Europe and North America, Ocimum basilicum, is among the more virtuosic of the herbs, and has been developed into several different flavor varieties, including lemon, lime, cinnamon, anise, and camphor. Most varieties of sweet basil are dominated by flowery and tarragon notes, though the variety used in Genoa to make the classic sauce pesto genovese is apparently dominated by mildly spicy methyleugenol and clove-like eugenol, with no tarragon aroma at all. Thai basil (O. basilicum and tenuiflorum) tends toward the anise-like and camphoraceous; Indian holy basil (O. tenuiflorum) is dominated by eugenol.

The flavor of basil depends not only on the variety, but on growing conditions and the stage at which it is harvested. Generally, aroma compounds make up a larger proportion of young sweet basil leaves than old, by as much as five times. In leaves that are still growing, the relative proportions of the different compounds actually vary along the length of the leaf, with the older tip richer in tarragon and clove notes, the younger base in eucalyptus and floral notes.

Bergamot This herb, also known as bee balm and Oswego tea, comes from a North American member of the mint family, Monarda didyma, whose aroma is somewhat lemony. The same name is given to a member of the citrus family whose essential oil is rich in flowery linalyl acetate, and which is the distinctive addition to Earl Grey tea. (Confusingly, European watermint [p. 404] is also sometimes called bergamot.) Horehound Horehound, so called for its hairy white (hoary) leaves, is a Eurasian species, Marrubium vulgare, with a musky and bitter flavor, more often used in candies than in cooking.

Mint family anatomy. A leaf of oregano, showing the microscopic oil glands that cover the surfaces of herbs in the mint family. The fragile, exposed glands filled with pungent essential oil offer a first line of defense against predators.

Hyssop Hyssop is an ambiguous name. It is sometimes applied to a kind of plant mentioned in the Bible and much used in the Middle East, a cluster of species characterized by the penetrating quality of true oregano (see below). Hyssop proper, Hyssopus officinalis, is a milder-mannered European herb with fresh-spicy and camphor notes. It was enjoyed in ancient Rome but is now more commonly used in Thai and Vietnamese cooking. Hyssop contributes to the flavors of several alcohols, including Pernod, Ricard, and Chartreuse.

Lavender Lavender is a Mediterranean plant long and widely valued for its tenacious floral-woody perfume (from a mix of flowery linalyl acetate and linalool, plus eucalyptus-like cineole), but more familiar in soaps and candles than in foods; its name comes from the Latin for “wash.” Still, the dried blossoms of Lavandula dentata are a traditional ingredient in the mixture herbes de provence (along with basil, rosemary, marjoram, thyme, and fennel). They and the blossoms of English lavender, L. angustifolia, are also useful alone when used discreetly as a garnish or to infuse their qualities in sauces and sweets. Spanish lavender (L. stoechas) has a complex scent reminiscent of Indian chutneys.

Lemon Balm Lemon or bee balm is an Old World species, Melissa officinalis, distinguished by its mixture of citrusy and floral terpenes (citronellal and -ol, citral, geraniol). Lemon balm is usually paired with fruit dishes and other sweets.

Marjoram Marjoram was once classified as coming from a sister genus of oregano, but now is officially a species of oregano itself, Origanum majorana. Whatever the precise family relationship, marjoram differs from the oreganos in having a milder flavor, fresh and green and floral, with little of their penetrating quality. It therefore works well as one component in many herb blends and dishes.

Mints The true mints are mainly small natives of damp habitats in Europe and Asia. There are about 25 species in the genus Mentha and some 600 varieties, though the family tendency to hybridizing and chemical variation confuses the picture. The mints of most interest to the cook are spearmint (Mentha spicata) and peppermint (M. piperata), which is an ancient hybrid between spearmint and watermint (M. aquatica).

Herbs of the Mint Family

Basil

Ocimum basilicum

Bergamot

Monarda didyma

Horehound

Marrubium vulgare

Hyssop

Hyssopus officinalis

Lavender

Lavendula dentata, L. angustifolia

Lemon balm

Melissa officinalis

Marjoram

Origanum majorana

Mints

Mentha species

Oregano

Origanum species

Perilla

Perilla frutescens

Rosemary

Rosmarinus officinalis

Sage

Salvia officinalis

Savory

Satureja species

Thyme

Thymus vulgaris

Both of the major culinary mints have a refreshing quality, but they are quite different. Spearmint has a distinctive aroma thanks to a particular terpene, L-carvone, and a richness and complexity thanks to pyridines, nitrogen-containing compounds more typical of roasted foods than raw ones. Spearmint is widely used in the Eastern Mediterranean as well as in India and Southeast Asia, in large quantities, both fresh and cooked, and in both sweet and savory contexts. Simpler, clearer-tasting peppermint contains little or no carvone or pyridines; instead it makes a terpene called menthol, which gives it a uniquely cooling quality. In addition to having its own aroma, menthol actually binds to receptors on temperature-sensing nerve cells in the mouth, and causes those cells to signal the brain that they are cooler than they really are by 7–13ºF/4–7ºC. Menthol is a reactive chemical that rapidly degenerates when heated, so peppermint is usually not cooked. Its concentration increases with the age of the leaf, so older leaves taste more cooling; hot and dry growing conditions cause menthol to be transformed into a noncooling, somewhat harsh by-product (pulegone, the characteristic volatile in pennyroyal).

A handful of other mints are worth knowing about. Watermint, one of the parents of peppermint and sometimes called bergamot or orange mint, has a strong aroma and used to be much cultivated in Europe, but now is more popular in Southeast Asia. Pennyroyal (M. pulegium) is an especially pungent, peppery minor mint, apple or pineapple mint (M. suaveolens) a sweet, apple-like one, and Mentha x piperata “citrata” the perfumy lemon or eau de cologne mint. Nepitella is the Italian name for Calamintha nepeta, a sometimes minty, sometimes pungent herb native to the southern Mediterranean, used in Tuscany to flavor pork, mushroom, and artichoke dishes. “Korean mint” comes from an anise-flavored Asian member of the mint family, Agastache rugosa.

Oregano There are about 40 species in the Mediterranean genus Origanum, most of them low, shrubby inhabitants of rocky places. The name comes from the Greek for “joy (or ornament) of the mountains,” though we have no evidence about how the Greeks enjoyed it. Oregano was little known in the United States until the rise of the pizza after World War II. Oregano species easily form hybrids with each other, so it’s not easy to sort out identities. The important thing for the cook is that they come in a range of flavors, from mild to strong and penetrating. The penetrating quality comes from the phenolic compound carvacrol. Greek oreganos are typically rich in carvacrol, while milder Italian, Turkish, and Spanish oreganos contain more thyme-like thymol and fresh, green, floral, and woody terpenes.

Mexican oregano is an entirely different plant, various species of the Mexican genus Lippia, a member of the verbena family. Some varieties do have a high carvacrol content, some more resemble thyme, and some are more woody and piney. They all have a substantially higher essential oil content than true oregano (3–4% in the dry leaf, vs. 1%), and therefore seem stronger.

Despite its name, Cuban oregano is an Asian member of the mint family, Plectranthus amboinicus, with fuzzy succulent leaves and a good dose of carvacrol. It’s now widely cultivated throughout the tropics; in India the fresh leaves are battered and fried.

Perilla or Shiso Perilla is the leaf of Perilla frutescens, a mint relative native to China and India. It was taken to Japan in the 8th or 9th century and named shiso; many Westerners get their first taste of it in sushi restaurants. The distinctive aroma of perilla is due to a terpene called perillaldehyde, which has a fatty, herbaceous, spicy character. There are several different perilla varieties, some green, some red to purple with anthocyanins, some with no perillaldehyde and instead tasting of dill or lemon. The Japanese eat the leaves and flower heads with seafood and grilled meats, and use a red variety to color and flavor the popular pickled plum, umeboshi. Koreans obtain both flavor and cooking oil from perilla seeds.

Rosemary Rosemary is a distinctive woody shrub, Rosmarinus officinalis, that grows in the dry Mediterranean scrublands, with leaves so narrow and tightly rolled that they look like pine needles. It has a strong, composite scent, made up of woody, pine, floral, eucalyptus, and clove notes. In southern France and Italy it traditionally flavors grilled meats, but it can also complement sweet dishes. Rosemary aroma is unusually well preserved by drying.

Sage The genus Salvia is the largest in the mint family, with around a thousand species that are rich in unusual chemicals, and have been used in many different folk medicines. The genus name comes from a Latin root meaning “health.” Sage extracts have been found to be excellent antimicrobial and antioxidant materials. However, common garden sage, S. officinalis, is rich in two terpene derivatives, thujone and camphor, that are toxic to the nervous system, so its use as anything but an occasional flavoring is not a good idea.

Common or Dalmatian sage has a penetrating, warm quality from thujone, the note of camphor, and a eucalyptus note from cineole. Greek sage (S. fruticosa) has more cineole, while clary sage (S. sclarea) is very different, with a tea-like quality and floral and sweet notes from a number of other terpenes (linalool, geraniol, terpineol). Spanish sage, S. lavandulaefolia, is fresher-smelling and less distinctive, with pine, eucalyptus, citrus, and other notes partly replacing thujone. Pineapple sage, S. elegans (rutilans), comes from Mexico and is said to have a sweet, fruity aroma.

Sage is especially prominent in northern Italian cooking, and in the U.S. flavors poultry stuffings and seasonings and pork sausages; it seems to have an affinity for fat. Most dried sage used to be “Dalmatian” sage, from the Balkan coast; today Albania and other Mediterranean countries are the largest producers. “Rubbed” sage is minimally ground and coarsely sieved leaves; it loses its aroma more slowly than finely ground sage.

Savory Savory comes in two types, which are two species of the northern-hemisphere genus Satureja. Both summer savory (S. hortensis) and winter savory (S. montana) taste like a mixture of oregano and thyme; they contain both carvacrol and thymol. Summer savory is often the milder of the two. It’s thought that savory may well be the parent genus of the various oreganos and marjoram. A native of western North America, S. douglasii, is known as yerba buena in California, and has a mild, mint-like flavor.

Thyme Thyme got its name from the Greeks, who used it as an aromatic in their burnt sacrifices; it shares its root with the words for “spirit” and “smoke.” There are a lot of thymes: 60–70 species in the shrubby, tiny-leaved, mainly Mediterranean genus Thymus, and as many or more varieties of the common thyme, Thymus vulgaris. There are also many flavors of thyme, including lemon, mint, pineapple, caraway, and nutmeg. A number of thyme species and varieties taste much like oregano because they contain carvacrol. Distinctive thyme species and varieties are rich in the phenolic compound called thymol. Thymol is a kinder, gentler version of carvacrol, penetrating and spicy, but not as aggressively so. It’s this moderate quality that probably endeared thymol thyme to the French, and that makes it a more versatile flavoring than oregano and savory; European cooks have long used it in meat and vegetable dishes of all kinds. Despite its gentler aroma, thymol is as powerful a chemical as carvacrol, which is why thyme oil has long been used as an antimicrobial agent in mouthwashes and skin creams.

The Carrot Family

Though the carrot family gave fewer flavoring plants to Europe than the mint family, it is remarkable for including several that provide aromatic interest as both herb and spice, and some even as vegetables. Members of the carrot family grow in less extreme conditions than the Mediterranean mints, are generally tender biennials rather than shrubby or woody perennials, and have flavors that are generally milder, sometimes even sweet. The seeds (actually small dry fruits) may have chemical defenses — and therefore are spices — because they’re fairly large and tempting to insects and birds. One terpene, myristicin, shared by dill, parsley, fennel, and carrots, and giving them a common woody, warm note, is thought to be a defense against molds. The aromatic compounds are stored in oil canals within the leaves, under large and small veins, and are generally found in smaller quantities than the externally stored defenses of the mint family.

Angelica Angelica is a large, rangy plant of northern Europe, Angelica archangelica, that has fresh, pine, and citrus notes, but is dominated by a sweet-smelling compound called the angelica lactone. Its candied stems were a popular delicacy from medieval times through the 19th century, but they’re seldom seen in the kitchen nowadays. Various parts of the plant now flavor gins, ver-mouths, liqueurs, candies, perfumes, and other manufactured products.

Celery Celery was a thin-stalked, aromatic but bitter herb called smallage before gardeners developed the mild, thick-stalked vegetable. Apium graveolens is a native of damp European habitats near the sea. The distinctive flavor of its leaves and stalks comes from compounds called phthalides, which it shares with lovage and with walnuts. It also has citrus and fresh notes. Celery is often simmered or sautéed with onions and carrots to provide a broad aromatic base for sauces and braises.

Chervil Chervil (Anthriscus cerefolium) has small, pale, finely divided leaves, and a delicate flavor that comes from relatively small amounts of the tarragon aromatic estragole; it’s best used raw or barely warmed, since heat drives away its flavor. Chervil is a component of the French mixture fines herbes.

Herbs of the Carrot Family

Angelica

Angelica archangelica

Celery

Apium graveolens

Chervil

Anthriscus cerefolium

Coriander leaf

Coriandrum sativum

Dill

Anethum graveolens

Fennel

Foeniculum vulgare

Lovage

Levisticum officinale

Mitsuba

Cryptotaenia japonica

Parsley

Petroselinum crispum

Saw-leaf herb

Eryngium foetidum

Coriander Coriander or cilantro is said to be the most world’s most widely consumed fresh herb. Coriandrum sativum is a native of the Middle East. Its seed has been found in Bronze Age settlements and in the tomb of King Tut; it was taken early to China, India, and Southeast Asia, and later to Latin America, and its rounded, notched, tender leaves are popular in all these regions. In Central and South America they came to replace culantro (p. 408), an indigenous relative with very similar flavor, but with large, tough leaves. Coriander herb is not very popular in the Mediterranean and Europe, where its aroma is sometimes described as “soapy.” The main component of the aroma is a fatty aldehyde, decenal, which also provides the “waxy” note in orange peel. Decenal is very reactive, so coriander leaf quickly loses its aroma when heated. It’s therefore used most often as a garnish or in uncooked preparations. In Thailand, the root of the herb is an ingredient in some pounded spice pastes; the root contains no decenal and instead contributes woody and green notes, something like parsley.

Dill Dill (Anethum graveolens) is a native of southwest Asia and India with tough stalks but very delicate, feather-like leaves. Dill was known in ancient Egypt, and became popular in northern Europe, perhaps thanks to its affinity with the local native caraway. Dillweed blends the distinctive flavor of its seed with pleasant green, fresh notes and a unique, characteristic note of its own (dill ether), and in Western cooking is most often used with fish. It is prepared in large amounts, almost as a vegetable and often with rice, in Greece and in Asia. India has its own distinctive variety, A. graveolens var. sowa, which is used as a vegetable as well as for its seeds.

Fennel Fennel is a native of the Mediterranean and southwest Asia; like dill, it has fibrous leaf stalks but feathery, tender leaves. There is one species of fennel, Foeniculum vulgare, and it comes in three different forms. The wild subspecies, piperitum, is sometimes collected from the countryside in southern Italy and Sicily, where it’s known as carosella and valued for its sharpness in meat and fish cooking. (Fennel now grows wild throughout central California as well.) The cultivated subspecies vulgare is known as sweet fennel thanks to its far richer content of the phenolic compound anethole, which is 13 times sweeter than table sugar, and also gives the characteristic sweet aroma of anise. And a specialized variety of sweet fennel, var. azoricum, develops the enlarged leaf-stalk bases of bulb or Florence fennel, which is used as an aromatic vegetable.

Lovage Lovage (Levisticum officinale) is a large western Asian plant that has aromat-ics in common with celery and oregano, along with a sweet, flowery note. It was used in ancient Greece and Rome and known as Ligurian celery. Today its large lobed leaves flavor beef dishes in central Europe, and tomato sauces in Liguria. Elsewhere it’s little known.

Carrot family anatomy. A leaf of parsley. Herbs in the carrot family have defensive oil glands within their leaves, not on the surfaces. The glands cluster around long canals and fill them with the essential oil.

Mitsuba Mitsuba, sometimes called Japanese parsley, is a native of both Asia and North America, Cryptotaenia japonica (or canadensis), whose mild, large leaves are used by the Japanese in soups and salads. They’re flavored mainly by a mixture of minor, woody-resinous terpenes (germacrene, selinene, farnesene, elemene).

Parsley Parsley is a native of southeast Europe and west Asia; its name comes from the Greek and means “rock celery.” Petroselinum crispum is one of the most important herbs in European cooking, perhaps because its distinctive flavor (from menthatriene) is accompanied by fresh, green, woody notes that are somewhat generic and therefore complement many foods. When parsley is chopped, its distinctive note fades, the green notes become dominant, and a faintly fruity note develops. There are both curly-and flat-leaf varieties with different characteristics; the flat leaves have a strong parsley flavor when young and later develop a woody note, while curly leaves start out mild and woody and develop the parsley character when more mature. The curly leaves are smaller and more incised and therefore crisp faster when fried.

Saw-Leaf Herb Saw-leaf herb or culantro is the New World’s version of coriander leaf (cilantro), still used in the Caribbean but now most commonly found in Asian cooking. There are more than a hundred species of Eryngium, some of them in Europe, but E. foetidum comes from subtropical South America, and is easier to grow in hot climates. Culantro has almost the same flavor as fresh coriander leaf, the main aromatic component being a slightly longer fatty aldehyde than coriander’s (dodecanal). Its leaves are large and elongated, with a serrated edge, and thicker and tougher than coriander leaves. They’re frequently used in Vietnamese dishes, often torn and strewn on just before eating.

The Laurel Family

The ancient laurel family, mostly large tropical trees, is most notable for giving us cinnamon; but it does give us one well-known herb and three less familiar but interesting ones. The leaves of various cinnamon species are also used as herbs in Asia, but are seldom seen in the West.

Avocado Leaf Mexican races of the avocado tree (Persea americana) have leaves with a distinct tarragon aroma, thanks to the same volatiles that flavor tarragon and anise (estragole, anethole). More tropical avocado races (p. 337) lack this aroma. In Mexico, avocado leaves are dried, then crumbled or ground to flavor chicken, fish, and bean dishes.

Bay Laurel

Bay leaves, one of the most useful European herbs, come from an evergreen tree or shrub native to the hot Mediterranean, Laurus nobilis. The medium-sized, tough, dry leaf accumulates oils in spherical glands in the leaf interior, and has a well-rounded mixture of woody, floral, eucalyptus, and clove notes. The leaves are generally dried in the shade. Laurel branches were made into fragrant crowns in the ancient world; today the leaves are a standard ingredient in many savory dishes.

California Bay California bay leaves come from an entirely different tree, the California native Umbellularia californica. Their aroma bears some resemblance to bay laurel, though it is distinctly stronger, with a dominant eucalyptus note (from cineole).

Sassafras or Filé Sassafras leaves come from a North American tree, Sassafras albidum. The Choctaw Indians introduced them to French settlers in Louisiana, and they are still most commonly encountered as the dry filé powder used to thicken and flavor Louisiana gumbos. They carry woody, floral, and green notes, and contain little or no safrole, a compound that’s prominent in the tree’s roots and bark, and that used to give root beer its characteristic flavor until it was found to be a likely carcinogen (see hoja santa below).

Other Common Herbs

Borage Borage is a medium-sized Mediterranean native, Borago officinalis, with bright blue flowers and large, fuzzy leaves that have the distinct flavor of cucumber, thanks to enzymes that convert its fatty acids into the same nine-carbon chain (nonanal) produced by cucumber enzymes. It was once a common ingredient of mixed salads (see the recipe on p. 251). Plants in the borage family accumulate potentially toxic alkaloids, so borage should be eaten in moderation.

Capers Capers are the unopened flower buds of a Mediterranean bush, Capparis spinosa, which have been gathered from the wild and pickled for thousands of years, though cultivated only for a couple of centuries. The caper bush is distantly related to the cabbage family and has its pungent sulfur compounds, which dominate in the raw flower bud. The bud is preserved in various ways — in brine, in vinegar, dry-salted — and used as a sour-salty accent in sauces and dishes, especially with fish. When drysalted, the caper bud undergoes an astonishing transformation: its radish and onion notes are displaced by the distinct aroma (from ionone and raspberry ketone) of violets and raspberries!

Curry Leaf Curry leaf is the leaf of a small tree in the citrus family, Murraya koenigii, a native of south Asia. It is primarily used in south India and Malaysia, where households often have their own plant and add it to many dishes. Despite its name, the curry leaf doesn’t taste like Indian curries; it is mild and subtle, with woody, fresh notes. Curry leaves are added to stews or other simmered dishes, or briefly sautéed to flavor a cooking oil. They are also remarkable for containing unusual alkaloids (carbazoles) with antioxidant and antiin-flammatory properties.

Curry Plant Curry plant is a Mediterranean member of the lettuce family, Helichrysum italicum, that has been said to be reminiscent of Indian curries. It does contain a number of terpenes that give it a vaguely spicy, pleasant aroma; it’s used to flavor egg dishes, teas, and sweets.

Epazote Epazote is a scented member of the large “goosefoot” family, which also provides us with spinach, beets, and the grain quinoa. Chenopodium ambrosioides is a weedy native of temperate central America that has spread throughout much of the world, and lends a characteristic aroma to Mexican beans, soups, and stews. That aroma is variously described as fatty, herbaceous, and penetrating, and is due to a terpene called ascaridole. Ascaridole is also responsible for the use of epazote in folk medicine; it is toxic to intestinal worms.

Hoja Santa This herb’s name is Spanish for “holy leaf,” and refers to the large leaf of New World relatives of black pepper, Piper auritum and P. sanctum. It’s used from southern Mexico to northern South America to wrap foods and flavor them while they’re cooked, and is also added directly to dishes as a flavoring. The main aromatic in hoja santa is safrole, the characteristic note of sassafras familiar from root beers, and a suspected carcinogen.

Houttuynia Houttuynia is a small perennial Asian plant, Houttuynia cordata, in the primitive lizard’s-tail family (Saururaceae), a relative of black pepper. Its leaves are used in Vietnamese and Thai salads, stews, and other dishes. There are two main varieties, one with a citrus aroma, and the other with an unusual scent said to resemble a mixture of meat, fish, and coriander.

Juniper Berries Juniper berries are not leaves, but their essence is the aroma of pine needles, so I include them here, along with the observation that pine and other evergreen needles are often used as flavorings. The Chinese steam fish over pine needles, and the original flavoring for salt-cured salmon (gravlax) was probably pine needles rather than dill. Pineyness is also one element in the aromas of many herbs and spices (see charts, pp. 392, 393).

There are about 10 species of Juniperus, a distant relative of the pine, all native to the northern hemisphere. They make small cone-like reproductive structures, about a third of an inch or 10 mm across, but the scales remain fleshy and coalesce to form a “berry” that surrounds the seeds. The berries take from one to three years to mature, during which they turn from green to purplish black. When immature, their aroma is dominated by the terpene pinene; when mature, they carry a mix of pine, green-fresh, and citrus notes. After two years in a spice bottle there is very little aroma left: so juniper berries are best when foraged and fresh. They are much used in northern Europe and Scandinavia to flavor meats, especially game, and cabbage dishes. Juniper is the distinguishing flavor in gin, and gave gin its name (originally Dutch genever).

Lemongrass Lemongrass is one of a small group of aromatic species in the grass family. Cymbopogon citratus accumulates the lemony terpene citral (a mixture of two compounds, neral and geranial), as well as flowery geraniol and linalool, in special oil cells in the middle of its leaves. It is a native of seasonally dry southern Asia, including the foothills of the Himalayas, and is important in the cooking of Southeast Asia. Lemongrass forms clumps of thick shoots; all parts are aromatic, but only the lower stalk is tender enough to be edible itself. The older outer leaves can be used to infuse a dish with their flavor, or be made into an herbal tea. In Thailand the tender stalk is a standard component of pounded spice pastes, and it’s also eaten fresh in salads.

Lemon Verbena Lemon verbena is a South American plant, Aloysia triphylla, a relative of Mexican oregano. The lemony flavor of its leaves comes from the same terpenes, collectively called citral, that flavor lemongrass; other terpenes lend a flowery note.

Lolot Lolot is the large, heart-shaped leaf of a black-pepper relative, Piper lolot, a native of Southeast Asia, and used there as a flavoring wrap for grilling meats.

Orange Flowers Orange flowers come from the bitter or Seville orange, Citrus aurantium, and they have been used for millennia to flavor sweets and other dishes in the Middle East, usually in the extract called orange-flower water. The distinctive perfume results from a mixture of terpenes also found in roses and lavender, with an important contribution from the same compound that flavors concord grapes (methyl anthranilate).

Makrut or Kaffir Lime Ma krut is the Thai name for the tree also known as kaffir lime (“kaffir” is Arabic for “unbeliever” and has derogatory connotations). This Southeast Asian member of the citrus family, Citrus hystrix, has distinctively aromatic leaves and fruit rinds that are an important ingredient in Thai and Laotian cooking, especially soups, stews, and fish dishes. The rind has an unremarkable mix of citrus, pine, and fresh notes, but the tough leaves are richly endowed with citronellal, which gives them an intense, fresh, lingering lemon-green character distinct from that of sweeter citral-flavored lemongrass (with which it’s often cooked). Citronellal is named for citronella, its original and main source, which is a sister species to lemongrass (Cymbopogon winterianus).

Nasturtium The flowers, leaves, and immature fruits of the familiar South American native Tropaeolum major all have a pungency like that of watercress, and enliven salads.

Nightshade Nightshade is a relative of the potato, Solanum torvum, which grows into a small and short-lived tree. It’s a native of the West Indies, but is now found throughout tropical Asia. Its small berry-like fruits are intensely bitter, and are used in Thailand, Malaysia, and Indonesia to contribute just that quality to sauces and salads.

Rau Ram Rau ram is the Vietnamese name for a sprawling herb in the buckwheat family known in English as fragrant knotweed, and now as Vietnamese cilantro. Polygonum odoratum is a native of Southeast Asia whose leaves mix the aromas of coriander and lemon with a slightly peppery taste. It’s often paired with mint, and eaten fresh with many foods.

Rice-Paddy Herb Rice-paddy herb is an aquatic plant in the snapdragon family, Limnophila chinensis ssp. aromatica, a native of Asia and the Pacific islands, whose small leaves are used in Southeast Asian fish dishes, soups, and curries, especially in Vietnam. It has a lemony but complex aroma produced by small quantities of a citrusy terpene and the main ingredient of perilla (perillaldehyde).

Rose Flowers Roses, mainly from the Eurasian hybrid Rosa x damascena, have been used for millennia from the Middle East through Asia, usually dried or in the form of an extract (rose water). Their aroma comes mainly from the terpene geraniol. Roses are most often used in sweets, but are also found in the savory Moroccan spice mixture ras el hanout, and in North African sausages.

Screwpine or Pandan Screwpine is the aromatic, strap-like leaf of shrubs related to the lily family that are native to Indonesia (species of Pandanus). Screwpine leaves are used in India and southeast Asia to flavor rice dishes and sweets, and to wrap meats and fish. Their primary volatile compound is the same one that gives basmati and jasmine rices their distinctive nutty aroma (2-acetyl-1-pyrroline, which is also prominent in the aroma of popcorn and of crabmeat). The screwpine flower is also aromatic and the source of a more perfume-like extract called kewra, which flavors many Indian milk sweets.

Sorrel Sorrel is the startlingly sour leaf of several European relatives of rhubarb and buckwheat that are rich in oxalic acid: Rumex acetosa, scutatus, and acetosella. Cooks use them mainly as a source of acidity, and they also provide a more generic green aroma. Sorrel readily disintegrates with a little cooking into a sauce-like puree that complements fish, but whose chlorophyll turns drab olive from the acidity. The color can be brightened by pureeing some raw sorrel and adding that to the sauce just before serving.

Tarragon Tarragon is the small, narrow leaf of a native of western and northern Asia, Artemisia dracunculus, a member of the lettuce family. The robust wild tarragon, often sold in plant nurseries as Russian tarragon, has a harsh and uninteresting flavor, while the relatively fragile cultivated form, “French” tarragon, has a distinctive aroma thanks to the presence of a phenolic compound called estragole (from the French name for the plant, estragon) in oil cavities alongside the leaf veins. Estragole is a close chemical relative of the anise aromatic anethole, and does have an anise-like character. Tarragon is a component of the French mix fines herbes, is the primary flavoring in béarnaise sauce, and is often used to flavor vinegars.

“Mexican tarragon” is a marigold-like New World native, Tagetes lucida, whose leaves do indeed contain a mixture of anise-like anethole and tarragon’s estragole.

Tobacco Tobacco is used occasionally as a food flavoring, and its curing resembles the making of tea (p. 437). The leaves of the notorious North American native Nicotiana tabacum, a relative of the potato and tomato, are harvested when they begin to turn yellow and develop resinous secretions, then either sun-cured or fermented in heaps for several weeks, and dried by contact with hot metal. These treatments develop a complex aroma with woody, leathery, earthy, and spicy notes, and these are sometimes augmented with the addition of various essential oils (vanilla, cinnamon, clove, rose, and others). Tobacco leaves contain astringent tannins and bitter nicotine, so they are usually infused only lightly into sauces, syrups, and creams. Sometimes whole leaves are used as a disposable wrapper to flavor a food during cooking.

Water Pepper Water pepper is a relative of rau ram, or Vietnamese coriander. Polygonum hydropiper is a widespread native of wet areas in the Northern Hemisphere. Its leaves have been used as a pepper substitute in Europe, and are now used mainly in Japan to provide a peppery, somewhat numbing pungency (from polygodial). Water pepper also has woody, pine, and eucalyptus notes.

Wintergreen Wintergreen is the leaf of Gaultheria procumbens or fragrantissima, a North American bush in the blueberry and cranberry family, whose distinctive, refreshing aroma is created mainly by methyl salicylate.

A Survey of Temperate-Climate
Spices

As is true of herbs, many of our temperate-climate spices come from just a few plant families. In the following survey, I group together spices that are botanically related, and list the rest in alphabetical order. Tropical spices are surveyed separately in the next section.

The Carrot Family

In addition to many leafy herbs, the carrot family also gives us a number of our favorite spices. The aromatic “seeds” of plants in the carrot family are actually small but complete fruits that are dry rather than fleshy. They are borne in pairs, enclosed in a protective husk, and are usually sold husked and separated. The individual fruits have a characteristic ridged surface, and their aromatic oil is contained in canals that lie under the ridges.

Ajwain Ajwain (Trachyspermum ammi) is a close relative of caraway, used in North Africa and Asia, especially India, and can be thought of as a seed version of thyme: it carries the essence of thyme, thymol, in a caraway-like seed.

Carrot family anatomy. Fennel seeds. Seeds of plants in the carrot family carry their essential oil in hollow chambers beneath their outer ridges.

Anise Anise is the seed of a small central Asian plant, Pimpinella anisum, which has been prized since ancient time. It’s remarkable for its high content of the phenolic compound anethole, which is both distinctively aromatic and sweet-tasting, and has been mainly used to flavor sweets and alcohols (Pernod, pastis, ouzo), though the Greeks also use it in meat dishes and tomato sauces.

Asafoetida Asafoetida is one of the strangest and strongest of all spices. It comes from a perennial plant in the carrot family native to the mountains of Central Asia, from Turkey through Iran and Afghanistan to Kashmir; India and Iran are major producers. Ferula asafoetida, F. alliacea, F. foetida, and F. narthex look something like giant carrot plants, growing to 5 feet/1.5 m and developing massive carrot-like roots 6 in/15 cm in diameter, from which new sprouts arise every spring. The spice is obtained after the new foliage begins to turn yellow. The top of the root is exposed, the foliage pulled out, and the root surface periodically scraped to wound it and gather the protective sap that collects in the wound. The sap slowly hardens and develops a strong, sulfurous aroma reminiscent of human sweat and washed-rind cheese (p. 58). Sometimes the resin is aged in fresh goat or sheep skin to augment its aroma, which is so strong that the resin is commonly ground and diluted for sale with gum arabic and flour. The aroma of asafoetida is due to a complex mixture of sulfur compounds, a dozen identical with volatiles in the onion family, and a number of less common di-, tri-, and tetrasulfides. Asafoetida can give the impression of onions, garlic, eggs, meat, and white truffles, and in India is a prominent ingredient in the cooking of the Jains, who avoid animal foods and also onion and garlic (because they contain a bud that would otherwise grow into a new plant).

Caraway Caraway comes from the small herb Carum carvi. There are annual and biennial forms, the first native to central Europe, the second to the Eastern Mediterranean and Middle East. The biennial form develops a taproot the first summer, then flowers and fruits the second; the taproots are sometimes cooked like carrots in northern Europe. Caraway may have been among the first spice plants cultivated in Europe; its seeds were found in ancient Swiss lake dwellings, and have continued to be an important ingredient in Eastern Europe. The distinctive flavor of caraway comes from the terpene D-carvone (which it shares with dill), with citrusy limonene the only other major volatile. Caraway is used in cabbage, potato, and pork dishes, in breads and cheeses, and in the Scandinavian alcohol aquavit.

Spices of the Carrot Family

Ajwain

Trachyspermum ammi

Anise

Pimpinella anisum

Asafoetida

Ferula asafoetida

Caraway

Carum carvi

Celery seed

Apium graveolens

Coriander

Coriandrum sativum

Cumin

Cuminum cyminum

Cumin, black

Cuminum nigrum

Dill seed

Anethum graveolens

Fennel seed

Foeniculum vulgare

Celery Seed

Celery seed is essentially a concentrated, dried version of the same aromas found in fresh celery (Apium graveolens), though of course it lacks the fresh green notes. The main aromas are a distinctive celery note from unusual compounds called phthalides, together with citrus and sweet notes. Celery seed was used in the ancient Mediterranean and is still common in European and American sausages, pickling mixes, and salad dressings. “Celery salt” is a mixture of salt and ground celery seeds.

Coriander Coriander (Coriandrum sativum) has been valued and cultivated since ancient times, more for its dried fruits than its leaves, which have entirely different flavors. The flavor of the fruit oil is startlingly floral and lemony, and makes coriander unique and irreplaceable in the cook’s arsenal of aromas. It’s generally used in combination with other spices, as a component of a pickling or sausage mix, in gin and other alcohols, or as half of the coriander-cumin backbone of many Indian dishes. Coriander is also one of the distinguishing flavors in American hot dogs.

There are two common types of coriander. The European type has small fruits (1.5–3 mm), a relatively high essential oil content, and a large proportion of flowery linalool; the Indian type has larger fruits (to 5 mm), a lower oil content, less linalool, and several aromatics not found in the European type.

Coriander seed is generally supplied whole, with the two dry fruits still enclosed in their husk. When it’s ground along with the aromatic fruits, the brittle, fibrous husk makes a good water absorber and thickener for sauces (the liquid portion of a curry, for example). Coarsely ground coriander is also used to coat meats and fish and provide flavor, crunch, and insulation at the same time.

Cumin Cumin comes from a small annual plant (Cuminum cyminum) native to southwest Asia, and was enjoyed by the Greeks and Romans; the Greeks kept it at the table in its own box, much as pepper is treated today. For some reason cumin largely disappeared from European cooking during the Middle Ages, though the Spanish kept it long enough to help it take root in Mexican cooking. The Dutch still make a cumin-flavored cheese, and the Savoie French a cumin bread, but cumin now mainly marks the foods of North Africa, western Asia, India, and Mexico. Its distinctive aroma comes from an unusual chemical (cuminaldehyde) that is related to the essence of bitter almond (benzaldehyde). It also has fresh and pine notes.

Black cumin is the seed of a different species (Cuminum nigrum), darker and smaller, with less cuminaldehyde and a more complex aroma. It is much used in savory dishes of North Africa, the Middle East, and North India.

Dill Seed Dill seed has a stronger flavor than dill weed, the feathery leaves of the same plant (Anethum graveolens). It’s mildly reminiscent of caraway thanks to its content of the caraway terpene carvone, but also has fresh, spicy, and citrus notes. It’s mainly used in central and northern Europe in cucumber pickles (the combination goes back at least to the 17th century), sausages, condiments, cheeses, and baked goods. Indian dill, var. sowa, produces a larger seed with a somewhat different balance of aromas; it’s used in spice mixtures of northern India.

Fennel Seed and Pollen Fennel seed has the same anise-like aroma and sweet taste as the stalk and leaves of the plant that bears it, Foeniculum vulgare. Its dominant volatile is the phenolic compound anethole (see anise, above), supported by citrus, fresh, and pine notes. Most fennel seed comes from sweet fennel varieties (p. 407) and tastes sweet; seed from the less cultivated types are also bitter due to the presence of a particular terpene (fenchone). Fennel seed is a distinctive ingredient in Italian sausages and in Indian spice mixes, and in India is chewed as an after-meal breath freshener.

The fine yellow pollen of the fennel flower is also collected and used as a spice. Fennel pollen combines anise and floral aromas, and in Italy is sprinkled on dishes at the last minute.

The Cabbage Family:
Pungent Mustards,
Horseradish, Wasabi

Of the various spices that manage to please us by causing irritation and pain, the mustards and their relatives are unique in providing a volatile pungency, one that travels from the food through the air to irritate our nasal passages as well as our mouth. The active ingredients of chillis and black pepper become significantly volatile only at high temperatures, above about 140ºF/ 60ºC, which is why roasting hot chillis or toasting peppercorns can cause everyone in the kitchen to start sneezing. But mustard and horseradish and wasabi can get into the nose even at room or mouth temperature. Theirs is a head-filling hotness.

The pungency of mustards and their relatives arises from the same chemical-defense system used by their vegetable relatives in the cabbage family (p. 321). The plants store their irritant defenses, the isothiocyanates, by combining them with a sugar molecule. The storage form is not irritating, but it does taste bitter. When their cells are damaged, special enzymes reach the storage form and break it apart, liberating the irritant molecules (and at the same time eliminating the bitterness). Mustard seeds and horseradish roots are pungent because we grind them up raw and encourage their enzymes to liberate the irritant molecules. When mustard seeds are cooked — for many Indian dishes they are toasted or fried until they pop — the liberating enzymes are inactivated, no irritants are liberated, and their flavor ends up nutty and bitter rather than pungent.

Mustards Mustard seed has been found in prehistoric sites from Europe to China, and was the first and only native pungent spice available to early Europe. It has been made into the familiar European condiment at least since Roman times; its name in most European languages comes not from the Latin name of the seed or plant (sinapis), but from the condiment, which was made with freshly fermented wine (mustum), and the hot (ardens) seeds. Different nations have distinctive prepared mustards whose roots go back as far as the Middle Ages. Mustard is also widely used as the whole seed, especially in Indian cooking, and flavors a broad range of dishes, including fruits preserved in sugar (Italian mostarda di frutta).

Black, Brown, and White Mustards There are three main kinds of mustard plants and seed, each with its own character.

• Black mustard, Brassica nigra, is a Eurasian native, small and dark-hulled, with a high content of the defensive storage compound sinigrin and therefore a high pungency potential. It was long important in Europe and still is in India, but is an inconvenient crop and in many countries has been replaced by brown mustard.
• Brown mustard, B. juncea, is a hybrid of black mustard and the turnip (B. rapa) that is easier to cultivate and harvest. It has large, brown seeds that contain somewhat less sinigrin than black mustard and therefore less potential pungency. Most European prepared mustards are made with brown mustard.
• White or yellow mustard, Sinapis alba (or Brassica hirta), is a European native with large pale seeds and a different defensive storage compound, sinalbin. The irritating portion of sinalbin is much less volatile than the irritant in sinigrin, so little of white mustard’s pungency rises into the nose. It mostly affects the mouth, and generally seems milder than black or brown mustard. White mustard is used mainly in the United States, in prepared mustards as well as whole in pickle mixes.

Making and Using Mustard Prepared mustard condiments can be made either from whole seeds or from powdered mustard, also called mustard flour, which has been ground and sieved to remove the seed coat. Dry mustard seeds and their powder are not pungent. Their pungency develops over the course of a few minutes or a few hours when the seeds are soaked in liquid and ground, or the preground seeds are simply moistened. The combination of moisture and cell damage revives the seeds’ enzymes and allows them to liberate the pungent compounds from their storage forms. Most prepared mustards are made with acidic liquids — vinegar, wine, fruit juices — which slow the enzymes, but also slow the later disappearance of the pungent compounds as they gradually react with oxygen and other substances in the mix.

Once the pungency has developed, cooking will drive off and modify the irritant molecules and so reduce the pungency, leaving behind a more generic cabbage-family aroma. Mustard is therefore usually added at the end of the cooking process.

Other Uses for Mustards In addition to their chemical defenses, mustard seeds are about a third protein, a third carbohydrate, and a third oil. When the seeds are ground, the small protein and carbohydrate particles and dissolved mucilage from the seedcoat can coat the surfaces of oil droplets and thus stabilize such sauce emulsions as mayonnaise and vinaigrette (p. 628). The seedcoat of white mustard is especially rich in mucilage (up to 5% of the seed weight), and ground white mustard is used in sausages to help bind the meat particles together.

Mustard oil is a traditional cooking oil in Pakistan and in Northern India, where it lends a distinctive flavor to Bengali fish dishes, pickles, and other preparations. In much of the West, the sale of mustard oil for food use is illegal, for two reasons: it contains large quantities of an unusual fatty acid, erucic acid; and it contains irritating isothiocyanates. Erucic acid causes heart damage in laboratory animals; its significance for human health isn’t known. Though our mustard condiments contain the same isothiocyanates as mustard oil, it’s possible that daily exposure through foods cooked in the oil could have harmful long-term effects. So far, medical studies are inconclusive. In Asia, it’s thought that preheating the oil to the smoking point reduces isothiocyanate content.

Horseradish Horseradish is a west Asian cabbage relative, Armoracia rusticana, remarkable for large fleshy white roots rich in sinigrin and its volatile pungent compound. Horseradish pungency develops when the raw root is grated, or when the ground dried root is rehydrated. Horseradish doesn’t seem to have been cultivated in Europe until the Middle Ages; today it’s used as a relish or dressing for meats and seafood, often in the company of cream to take the edge off its strong flavor.

Wasabi Wasabi is the enlarged stem of an East Asian cabbage relative that also accumulates sinigrin as a chemical defense. Wasabia japonica is a native of Japan and Sakhalin Island, where it grows alongside cool mountain streams. Wasabi is now cultivated in several countries and is occasionally available fresh in the West; whole and partly used roots keep for several weeks in the refrigerator.

Most wasabi served in restaurants is in fact ordinary dried horseradish powder, colored green and reconstituted with water. It has a similar pungency, but little else in common with true wasabi. When the fresh stem is grated a few minutes before the meal, it releases more than 20 enzyme-generated volatiles, some pungent, some oniony, some green, some even sweet.

The Bean Family:
Licorice And Fenugreek

Licorice Licorice comes from the roots of Glycyrrhiza glabra, a native of southwest Asia. Its English name is a much-altered version of its genus name, which derives from the Greek for “sweet root.” The woody roots of this shrub are remarkable for containing a steroid-like chemical, glycyrrhizic acid, that is 50–150 times sweeter than table sugar. The water extract of the roots contains many different compounds, including sugars and amino acids, which undergo flavor-and pigment-producing browning reactions with each other when the extract is concentrated. Licorice extracts are available as dark syrups, blocks, or powders, and are used in various confections, to give color and flavor to dark beers, porter, and stout, and to flavor tobacco for cigars, cigarettes, and chewing. Many licorice candies are flavored with anise-like anethole (p. 414), but licorice root itself has a more complex aroma, with almond and floral notes.

Thanks to its hormone-like chemical structure, glycyrrhizic acid has a number of effects on the human body, some helpful and some not. It helps soothe coughs, but it also can disrupt normal regulation of mineral and blood pressure levels. Licorice is therefore best consumed in moderation and infrequently; daily consumption can sometimes cause a significant rise in blood pressure and other problems.

Fenugreek Fenugreek is the small, hard seed of a bean relative, Trigonella foenumgraecum, that’s native to southwest Asia and the Mediterranean. Its name comes from the Latin for “Greek hay.” Fenugreek is somewhat bitter and has a very distinctive sweet aroma, reminiscent of dry hay as well as maple syrup and caramel, that comes from a chemical called sotolon, which is also an important volatile in molasses, barley malt, coffee, soy sauce, cooked beef, and sherry. The outer cell layer of the fenugreek seed contains a water-soluble storage carbohydrate (galactomannan), so that when the seeds are soaked, they exude a thick, mucilaginous gel that gives a pleasant slipperiness to some Middle-Eastern sauces and condiments (Yemen’s hilbeh). Fenugreek is a component of various spice mixtures, including Ethiopian berber and some Indian curry powders.

Fenugreek leaves are bitter and slightly aromatic, and are enjoyed as a fresh or dried herb in India and Iran.

Chillis

Chillis, or “chile peppers,” the fruits of small shrubs native to South America, are the most widely grown spice in the world. Their active ingredient, the spectacularly pungent chemical capsaicin, protects the seeds of the chilli fruit, and appears to be a chemical repellant aimed specifically at mammals. Birds, which swallow the fruits whole and disperse the seeds widely, are immune to capsaicin; mammals, whose teeth grind up the fruit and destroy the seeds, are pained by it. It’s a wonderfully perverse achievement for our mammal species to have fallen in love with this anti-mammalian weapon and spread the chillis much further than any bird ever did!

The success of the chilli has been remarkable. World production and consumption are now some 20 times that of the other major pungent spice, black pepper. It is ubiquitous in Central and South America, Southeast Asia, India, the Middle East, and North Africa. In China the chilli is a major spice in Sichuan and Hunan provinces; in Europe, Hungary has its paprika and Spain its pimenton. In the United States, salsas became more popular than ketchup in the 1980s, thanks to the influence of Mexican restaurants. Mexico remains the most advanced chilli culture, where several different varieties may be blended to obtain a particular flavor, and where the substance of many sauces is contributed by chillis, without the aid of flavorless flours or starches.

Chillis and Capsaicins There are about 25 species of Capsicum, most natives of South America, of which five have been domesticated. Most of our common chillis come from one species, Capsicum annuum, which was first cultivated in Mexico at least 5,000 years ago. Chillis are hollow fruits, with an outer wall rich in carotenoid pigments that encloses the seeds and the tissue that bears them, a pale, spongy mass called the placenta. (For chillis as vegetables, see p. 331). Their pungent chemicals, the capsaicins, are only synthesized by the surface cells of the placenta, and accumulate in droplets just under the cuticle of the placenta surface. That cuticle can split under the pressure and allow the capsaicin to escape and spread onto the seeds and the inner fruit wall. Some capsaicin also seems to enter the plant’s circulation, and can be found in small quantities within the fruit wall and in nearby stems and leaves.

The amount of capsaicin that a chilli contains depends not only on the plant’s genetic makeup, but on growing conditions — high temperatures and drought increase production — and on its ripeness. The fruit accumulates capsaicin from pollination until it begins to ripen, when its pungency declines somewhat: so maximum pungency comes around the time that the green fruit begins to change color.

There are several different versions of the capsaicin molecule found in chillis. This may be why different kinds of chillis seem to produce different kinds of pungency — quick and transient, slow and persistent — and to affect different parts of the mouth.

Capsaicin’s Effects on the Body The effects of capsaicin on the human body are many and complex. As I write in 2004, the scorecard is fairly positive. Capsaicin does not appear to increase the risk of cancer or stomach ulcers. It affects the body’s temperature regulation, making us feel hotter than we actually are, and inducing cooling mechanisms (sweating, increased blood flow in the skin). It increases the body’s metabolic rate, so that we burn more energy (and therefore retain less in storage as fat). It may trigger brain signals that make us feel less hungry and more satiated. In sum, it may encourage us to eat less of the meal it’s in, and to burn more of the calories that we do eat.

Of course there’s also capsaicin’s irritating effects, which can be pleasurable in the mouth but not necessarily elsewhere. (This is why “pepper spray” is an effective weapon; it makes breathing and seeing difficult for about an hour.) Capsaicin is potent and oily and hard to wash off surfaces, so small amounts left on fingers can end up hours later being rubbed into an eye. Knives, cutting boards, and hands should be thoroughly washed with hot soapy water to avoid this and similar unhappy surprises. On the other hand, capsaicin irritation has found a number of medical applications; for example, when applied to the skin it helps reduce muscle pain by increasing local blood flow.

The chilli fruit. The pungent chemical capsaicin is secreted by cells on the surface of the placenta, the pithy tissue that bears the seeds.

Controlling Capsaicin Pungency The pungency of any dish that contains chillis is influenced by four main factors: the variety of chilli used, the amount of chilli added, the presence or absence of the capsaicin-rich tissues, and the length of time that the chilli is in contact with the other ingredients. The cook can reduce the pungency of chillis substantially by cutting them in half and carefully dissecting and removing the spongy placental tissue and the seeds.

What about quenching the burn once the mouth is already on fire? The two surest remedies — though they’re only temporary — are to get something ice-cold into the mouth, or something solid and rough, rice or crackers or a spoonful of sugar. Cold liquid or ice cools the receptors down below the temperature at which they are activated, and the rough food distracts the nerves with a different kind of signal. Though capsaicin is more soluble in alcohol and oil than it is in water, alcoholic drinks and fatty foods appear to be no more effective than cold or sweetened water at relieving the burn (carbonation adds to the irritation). If all else fails, take comfort in the fact that capsaicin pain generally fades within 15 minutes.

Dried Chillis Dried chillis are much more than a conveniently stable source of pungency and thickening power: they’re the source of flavor complexity that is rare even among herbs and spices. The drying process concentrates the contents of the cells in the fruit wall, encouraging them to react with each other and generate dried-fruit, earthy, woody, nutty, and other aromatics. Drying traditionally took several weeks in sun or shade, and in much of the world it still does. Modern machine drying offers more control, and can minimize the loss of light-sensitive pigments and vitamin C, though it brings flavor differences as well. Chillis are sometimes smoke-dried (Mexican chipotles, some Spanish pimentons), which lends a characteristic note.

Other Temperate-Climate Spices

Hops Hops are the dried seed-bearing “cones” of Humulus lupulus, a perennial native of the Northern Hemisphere that is a relative of marijuana and hemp. The hop plant was cultivated in the Hallertau region of Germany by the 8th century, and spread to Flanders by the 14th. Though now used almost exclusively in beer, they also flavor bread and are made into an herbal tea. Hop aroma depends on the variety, and may include woody, floral, and complex sulfur notes. It’s described in more detail in chapter 13.

Mahleb Mahleb or mahaleb is the dried kernel of a small kind of cherry native to Iran, Prunus mahaleb. The kernels have a warm aroma vaguely suggestive of bitter almond, and are used to flavor baked goods and sweets in much of the eastern Mediterranean.

Mastic Mastic is a resin exuded from the trunk of a relative of the pistachio, Pistacia lentiscus, a tree native to the Eastern Mediterranean that now grows only on the Greek island of Chios. Mastic was chewed like chewing gum (hence its name, from the same root as masticate), and is also used to flavor various preparations, from breads and pastries to ice cream, candies, and alcohol (ouzo). The main aromatic components of the gum are two terpenes, pine-like pinene and woody myrcene. Myrcene is also the molecule from which the long resin polymers are built. The resin is not very soluble in water, so it must be ground fine and mixed with another powdery ingredient (flour, sugar) to help disperse it evenly in liquid ingredients.

Chilli Variety

Pungency, Scoville Units

Capsicum annuum

Bell

0–600

New Mexican

500–2,500

Wax

0–40,000

Paprika

0–2,500

Pimento

0

Jalapeno

2,500–10,000

Ancho/ poblano

1,000–1,500

Serrano

10,000–25,000

Cayenne

30,000–50,000

Capsicum chinense

Habanero, scotch bonnet

80,000–150,000

Capsicum frutescens

Tabasco

30,000–50,000

Capsicum pubescens

Rocoto

30,000–60,000

Capsicum baccatum

Aji

30,000–50,000

Nigella The small, black, angular seed of Nigella sativa, a close Eurasian relative of the common ornamental plant love-in-a-mist, tastes like a milder, more complex version of thyme or oregano, with a hint of caraway. It’s used from India through southwest Asia in breads and other dishes.

Saffron Saffron is the world’s most expensive spice: a testament not only to the labor required to produce it, but to its unique ability to impart both an unusual flavor and an intense yellow color to foods. It is a part of the flower of a kind of crocus, Crocus sativus, which was probably domesticated in or near Greece during the Bronze Age. The saffron crocus was carried eastward to Kashmir before 500 BCE; in medieval times the Arabs took it westward to Spain, and the Crusaders to France and England. (The name comes from the Arabic for “thread.”) Today Iran and Spain are the major producers and exporters. They use saffron in their respective rice dishes, pilaf and paella; the French in their fish stew, bouillabaisse; the Italians in risotto milanese; the Indians in biryanis and milk sweets.

The numbers that figure in saffron production are startling. It takes about 70,000 crocus flowers to produce 5 lb/2.25 kg of stigmas, the three dark red ends of the tube (“style”) that carries pollen down to the plant’s ovary. These 5 pounds in turn dry down to about 1 lb/450 gm of saffron. And because they’re so delicate, the stigmas are still harvested and separated from the other flower parts by hand, with nearly 200 hours of labor required for that same 1 pound of dried saffron. Each purple-petaled flower must be harvested on the same day that it begins to open, in late autumn. Once separated, the stigmas are carefully dried, either with a 30-minute toasting over a fire (Spain), or longer times in the sun (Iran), or in a warm room or modern oven.

Saffron Color Saffron’s intense color comes from a set of carotenoid pigments (p. 267) that account for 10% or more of the dried spice’s weight. The most abundant form, called crocin, is a molecular sandwich of one pigment molecule with a sugar molecule attached at each end. The sugars make the normally oil-soluble pigment into a water-soluble one — and this is why saffron is easily extracted in hot water or milk and works so well as a coloring agent for rice and other nonfatty foods. Crocin is a powerful colorant, and gives a noticeable tinge to water even at 1 part per million.

The saffron crocus. Pure saffron consists of the dried stigmas, the deep red tips that catch pollen grains and send them down the long style to the ovary. Second-quality saffron often includes the pale, relatively flavorless styles.

Saffron Flavor Saffron flavor is characterized by a notable bitterness and a penetrating, hay-like aroma. It arises largely from another sugar-hydrocarbon combination, picrocrocin, which may be up to 4% of the fresh weight of the stigmas, and is probably a defense against insects and other predators. The combination itself is bitter. When the stigmas dry out and their cell structures are damaged, both the drying heat and an enzyme act on picrocrocin to liberate the hydrocarbon portion, which is a volatile terpene called safranal. Drying the saffron stigmas thus moderates the bitterness and develops the aroma. Several chemical relatives of safranal round out the overall aroma.

Using Saffron Saffron is typically used in small quantities — a few threads, or a “pinch” — and rehydrated in a small amount of warm or hot liquid before being added to a dish, in order to extract both flavor and color. The main pigment is water soluble, but the inclusion of some alcohol or fat in the extraction liquid will dissolve additional fat-soluble carotenoids.

Saffron’s color and flavor molecules are readily altered by light and heat, so this valuable spice is best stored in an airtight container in the freezer.

Sumac Sumac is the small, dried, purplered berry of a shrubby relative (Rhus coriaria) of the cashew and mango trees, a native of southwest Asia. Sumac is unusual for being very tart (from malic and other acids), astringent (from abundant tannins, to 4% of its weight), and aromatic, with pine, woody and citrus notes. Sumac is ground and added to a number of savory dishes in the Middle East and North Africa.

A Survey of
Tropical Spices

Among the tropical spices, family relationships don’t readily translate into flavor relationships. I’ve therefore listed them all in simple alphabetical order. It’s interesting to note, though, that the ginger family includes turmeric, galangal, cardamoms, and grains of paradise; and that allspice and clove are members of the myrtle family, and thus relatives of each other and of two strong-scented fruits, guava and feijoa.

Allspice Allspice is the brown, mediumsized dried berry of a tree of the New World tropics. Pimenta dioica is a member of the myrtle family and a relative of the clove. Allspice took on its modern name in the 17th century because it was thought to combine the aromas of several spices, and today it’s often described as tasting like a mellow combination of clove, cinnamon, and nutmeg. It is indeed rich in clove’s eugenol and related phenolic volatiles, with fresh, sweet, and woody notes (but no cinnamon volatiles). The main producer is Jamaica. The berries are picked when green and at the height of flavor, briefly fermented in heaps, “sweated” in bags to accelerate their drying and browning, then sun-dried for five to six days (or machine-dried). Allspice finds notable use in pickling fish, meats, and vegetables, as well as in pie seasonings.

Annatto Annatto, also known as achiote, is both a flavoring and a colorant. It is the seed of a bush, Bixa orellana, native to tropical America, and is much used in various cooked dishes from southern Mexico to northern South America. The bright red-orange pigment bixin is found in the waxy coating of the seeds, and readily changes into a number of chemical variants that are different shades of orange, yellow, and red. Some of these are soluble in water, others in oil; large food manufacturers use annatto extracts to give a vivid color to cheddar-style cheeses, butter, and other products. Annatto seeds are hard, and difficult to grind finely, so they’re often heated in a liquid to extract their flavor and color and then are strained out. Commercially ground annatto pastes are also available. The aroma of annatto is dominated by the woody, dry terpene humulone, which is also found in hops.

Cardamom Cardamom is the world’s third most expensive spice after saffron and vanilla. It’s the seed of a herbaceous plant in the ginger family that is indigenous to the mountains of southwest India, and was grown only there until around1900. German immigrants then brought it to Guatamala, which is now the largest producer. Cardamom seeds are borne in clusters of fibrous capsules that ripen at different times, so the capsules must be picked by hand one by one, and slightly before full ripeness, when the capsule splits. The word comes from an Arabic root meaning “to warm”; and cardamom has a delicate, warming quality due to two different sets of aromatics, both stored in a layer just below the seed surface: a group of floral, fruity, and sweet terpene compounds (linalool and acetate esters), and more penetrating, eucalyptus-like cineole.

There are two broadly different varieties of cardamom: Malabar, a small, round capsule with a high content of delicate, flowery compounds, and Mysore, a larger, three-angled capsule with mainly pine, woody, and eucalyptus notes. Both are slightly astringent and pungent. Malabar cardamom develops its best flavor after the pods have begun to turn from green to off-white, so it is usually available only in bleached form, after sun-drying or chemical bleaching to make the pod color more uniform. Mysore cardamom is often sold green, its color fixed by a three-hour dose of moderate heat (130ºF/55ºC) before drying.

Cardamom is mentioned along with cinnamon in the Old Testament, but doesn’t seem to have reached Europe until the Middle Ages. Today the Nordic countries consume 10% of world trade, mainly in baked goods, while Arab countries take 80% for their cardamom coffee. Gahwa is made by boiling together freshly roasted and ground coffee with freshly broken green cardamom pods.

Large cardamom, also called Nepal or greater Indian cardamom, is the seed of a cardamom relative, Amomum subulatum, which grows in the eastern Himalayas of North India, Nepal, and Bhutan. (Other species of Amomum and Aframomum are also used.) The seeds are borne in a reddish pod an inch/2.5 cm long, with a sweet surrounding pulp. Large cardamom has a strong, harsh flavor for two reasons: much of the crop is smoke-dried, and the seeds are rich in the penetrating terpenes cineole and camphor. Large cardamoms are often used in India, west Asia, and China in savory and rice dishes and in pickles.

Cinnamon Cinnamon is the dried inner bark of trees in the tropical Asian genus Cinnamomum, a distant relative of the bay laurel. Its inner bark or phloem layer, which carries nutrients from the leaves toward the roots, contains protective oil cells. When the inner bark is cut and peeled from the new growth of these trees, it curls to form the familiar long “quills” or sticks. Cinnamon was one of the first spices to reach the Mediterranean; the ancient Egyptians used it in embalming, and it’s mentioned repeatedly in the Old Testament. Asian and Near Eastern peoples have long used cinnamon to flavor meat dishes, and thanks to the influence of the Arabs, medieval European cooks did too. Nowadays most cinnamon goes into sweet dishes and candies.

There are several different species of Cinnamomum that provide aromatic bark, but cinnamons fall into two general categories. One is Ceylon or Sri Lankan cinnamon (from C. verum or zeylanicum), light brown in color, papery and brittle, coiled in a single spiral, and with a mild, delicate cinnamon flavor often described as sweet. The other is the Southeast Asian or Chinesecinnamon, often called cassia, which is typically thick and hard, forming a double spiral, darker in color and much stronger in flavor, bitter and somewhat harsh and burning, as in the American “red-hot” candy. These cinnamons come mainly from China (C. cassia), Vietnam (C. loureirii), and Indonesia (C. burmanii). Cassia types are preferred in most of the world, Sri Lankan types in Latin America. The typical hot, spicy cinnamon aroma comes from a phenolic compound, cinnamaldehyde, of which cassia types have significantly more than Sri Lankan types; the latter are more subtle and complex, with floral and clove notes (linalool, eugenol).

Cloves Cloves are among the most distinctive and strongest of all spices. They’re the dried immature flower buds of a tree in the myrtle family, Syzygium aromaticum, which is native to a few islands in present-day Indonesia. Cloves were enjoyed in China 2,200 years ago, but weren’t much used in European foods until the Middle Ages. Today Indonesia and Madagascar are the biggest producers.

The flower buds of the clove tree are picked just before they open, and then dried for several days. Their distinctiveness results from a high content of the phenolic compound called eugenol, which has a unique aroma that is both somewhat sweet and very penetrating. Clove buds contain the highest concentration of aroma molecules of any spice. They are as much as 17% volatile chemicals by weight, most of this stored just under the surface of the elongated portion, in the flower cap, and in the delicate filaments of the stamens within. The oil is about 85% eugenol. Thanks mainly to eugenol, clove oil is good at suppressing microbes, and it temporarily numbs our nerve endings, properties that have led to its use in mouthwashes and dental products.

In much of the world cloves flavor meat dishes, while Europeans use them mainly in sweets. Cloves are an important element in a number of spice mixes (see box, p. 398). By far their largest role is in the Indonesian flavored cigarette, kretek, which may be 40% shredded clove.

Galangal Galangal is a name given to the underground stem, or rhizome, of two Asian ginger relatives, Alpinia galanga or greater galangal, and Alpinia officinarum or lesser galangal. The former, sometimes also called Thai ginger, is the more prized and common. Galangal is more austere than ginger, pungent and with overtones of eucalyptus, pine, clove, and camphor, but none of ginger’s lemony character. In Thai and other Southeast Asian cuisines it’s often combined with lemongrass and many other aromatics. Galangal is also an ingredient in Chartreuse, bitters, and some soft drinks.

Ginger Ginger is the pungent, aromatic rhizome of a herbaceous tropical plant, Zingiber officinale, that is distantly related to the banana. It lends its name to a family of about 45 genera that are found throughout the tropics, and that include galangal, grains of paradise, cardamom, and turmeric. The name comes via Latin from the Sanskrit singabera, meaning horns or antlers, which the branched rhizomes resemble.

Ginger was domesticated in prehistoric times somewhere in southern Asia, had been brought in dried form to the Mediterranean by classical Greek times, and was one of the most important spices in medieval Europe. The cake known as gingerbread dates from this time; ginger beer and ginger ale from the 19th century, when English taverns sprinkled powdered ginger on their drinks.

To make the dried spice, mature rhizomes are cleaned, scraped to remove most of the skin, sometimes treated with lime or acid to bleach them, and then dried in the sun or a machine. Dried ginger is about 40% starch by weight. Today the main producers of dried ginger are India and China, while Jamaican ginger is considered one of the finest. A surprisingly large fraction of the ginger trade goes to Yemen, where it is added to coffee (as much as 15% of the coffee’s weight).

In Asia, and increasingly in the rest of the world, ginger is used fresh. Most fresh ginger in the United States now comes from Hawaii, where the main harvest runs from December to June. Fresh ginger contains a protein-digesting enzyme that can cause problems in gelatin-based preparations (p. 607).

Ginger Aromas Ginger has a remarkable culinary range, flavoring sausages and fish dishes as well as sodas and sweets. It has something of the quality of lemon juice in that it adds a refreshing, bright aroma — from fresh, floral, citrus, woody, and eucalyptus notes — and mild, pepper-like pungency that complements other flavors without dominating them. Gingers from different parts of the world have different qualities. Chinese ginger tends to be mainly pungent; South Indian and Australian gingers have a notable quantity of citral and so a more distinctly lemony aroma; Jamaican ginger is delicate and sweet, African ginger penetrating.

Ginger Pungency Is Variable The pungency of ginger and members of its family comes from the gingerols, chemical relatives of the chilli’s capsaicin and black pepper’s piperine (p. 394). The gingerols are the least powerful of the group, and the most easily altered by drying and cooking. When ginger is dried, its gingerol molecules lose a small side group of atoms and are transformed into shogaols, which are about twice as pungent: so dried ginger is stronger than fresh. Cooking reduces ginger pungency by transforming some gingerols and shogaols into zingerone, which is only slightly pungent and has a sweet-spicy aroma.

Grains of Paradise Grains of paradise, guinea grains, alligator pepper, and melegueta pepper are all names for the small seeds of Aframomum melegueta. This member of the ginger family is a native of West Africa, and was used in Europe from the Middle Ages until the 19th century, when it became a rarity. It’s both somewhat pungent from gingerol and relatives (paradols, shogaols), and faintly but pleasantly aromatic, with woody and evergreen notes (humulone and caryophyllene). It is a component of the Moroccan spice mixture ras el hanout, and can serve as an interesting alternative to black pepper.

Mace and Nutmeg Mace and nutmeg have similar aromas and come from the same source: the fruit of a tropical Asian tree, Myristica fragrans, which appears to have originated in New Guinea. Along with cloves, nutmeg put the Spice Islands, the Malaccas that are now part of Indonesia, on the maps of European sea powers. The Portuguese and then the Dutch monopolized the nutmeg trade until the 19th century, when the tree was successfully planted in the Caribbean and elsewhere. Nutmeg and mace didn’t make much of an impression on European foods until the Middle Ages. Today they provide the characteristic flavoring for doughnuts and eggnog, and are added to hot dogs and other sausages. Nutmeg is also an important element of the classic French béchamel sauce.

Both nutmeg and mace are borne inside the plum-to peach-sized fruits of the tree. When the fruit is ripe, it splits to reveal a shiny, brown-black shell; and entwined around the shell, a narrow, irregular, bright red ribbon. The red ribbon is an aril, a fruit part whose color and sugars attract birds to carry it and the seed away. The aril is the spice called mace, and the seed inside the shell is the nutmeg. The aril is removed from the shell and dried separately. The aroma compounds in nutmeg are concentrated in a layer of oil-containing tissue that weaves through the seed’s main body of starchy and fatty storage tissue, which also contains astringent tannins.

Nutmeg and mace have similar but distinct flavors, with mace the gentler and more rounded. Both spices carry fresh, pine, flowery, and citrus notes, but are dominated by woody, warm, somewhat peppery myristicin (also a minor component in fresh dill). Grated nutmeg includes tannic particles of the main seed storage tissue, and is also darker in color than powdered mace. Nutmeg has generally been put to use in sweets and dishes based on cream, milk, and eggs; mace in meat dishes as well as pickles and ketchups. Their flavors tend to become unpleasant with prolonged heat, so they’re often grated over a dish at the last minute.

Nutmeg is reputed to have hallucinogenic effects if several grated seeds are consumed at once. Myristicin has been suggested as the active ingredient, but the evidence is scanty.

Black Pepper and Relatives Black pepper was one of the first spices to be traded westward from Asia, and today it remains the preeminent spice in Europe and North America. We think of it as a basic seasoning, like salt, and use its moderate pungency and pleasant aroma to fill out the flavor of many savory dishes, often just before eating them. Pepper is native to the tropical coastal mountains of southwest India, where sea and overland trade with the ancient world began at least 3,500 years ago. It is mentioned in Egyptian papyruses, was well known to the Greeks, and a popular spice in Rome. During this time it was largely gathered from wild forest plants, though sometime before the 7th century the vine was transplanted to the Malay archipelago, Java, and Sumatra.

Vasco da Gama discovered the sea route from Europe to southwest India in 1498, and the Portuguese subsequently controlled exports of black pepper for several decades. They were followed by the Dutch and, beginning around 1635, the British, who established pepper plantations. In the 20th century, a number of countries in South America and Africa began producing black pepper. Today India, Indonesia, and Brazil are the major world sources.

Pepper Production Black pepper is the small dried berry of a climbing vine in the genus Piper, which includes a number of other spice and herb plants (see box, p. 429). The berries of Piper nigrum form on a flower spike a few centimeters long, and take about six months to mature. As berries mature and ripen, their content of pungent piperine continuously increases, while their aromatics reach a peak and then decline. Fully ripe berries may contain less than half of the aroma that they had at the late green stage. The ripe berry skin is red, but turns dark brown to black after harvest thanks to the activity of browning enzymes. The inner seed is largely starch, with some oil, from 3–9% pungent piperine, and 2–3% volatile oil.

Black, White, Green, and Rose-Colored Peppers Pepper berries are processed to make several different versions of the spice.

Black and white pepper. Pepper comes from the small fruits of a tropical vine. Black pepper is made by drying the whole fruit; the wrinkled dark outer coating is the dried fleshy fruit layer. White pepper is made by removing the fleshy layer before drying the seed.

• Black pepper, the most common, is made from mature but unripe berries, still green and rich in aromatics. The berry spikes are harvested from the vines and the berries threshed from the spikes. The berries are then blanched for a minute in hot water to clean them and rupture the cells of the fruit layer to speed the work of the browning enzymes. Finally they’re sun-or machine-dried for several days, during which the outer fruit layer darkens.
• White pepper consists of the pepper seed only, without the outer fruit layer. It’s made from fully ripe berries, which are soaked in water for a week to allow the fruit layer to be degraded by bacteria, then rubbed to remove the fruit layer, and finally dried. White pepper is mainly valued for providing pungency while remaining invisible in light-colored sauces and other preparations. It was developed into a major commercial product in Indonesia, which is still its major producer.
• Green pepper is made from berries harvested a week or more before they would otherwise begin to ripen. The berries are simply preserved by treating with sulfur dioxide and dehydration, by canning or bottling in brine, or by freeze-drying. The flavor depends on the method of preservation, but includes some pungency and pepper aromatics as well as a fresh green-leaf note.
• Pink pepper, or poivre rose, is a rarity made by preserving just-ripened red berries in brine and vinegar. (Pink peppercorns are entirely different; see below.)

Pepper Flavor The main pungent compound in pepper is piperine, which is found in the thin fruit layer and the surface layers of the seed. Piperine is about 100 times less pungent than the capsaicin in chillis. The major aroma components in black pepper (the terpenes pinene, sabinene, limonene, caryophyllene, linalool) create an overall impression that is fresh, citrusy, woody, warm, and floral. White pepper is about as pungent as black pepper, but lacks much of its aroma due to the removal of the outer fruit layer. It often has musty and horse-stable notes, probably from the prolonged fermentation of the fruit layer (skatole, cresol).

Pepper is used in the form of whole “corns” in preparations that allow time to extract their flavor: such things as pickles and preserves, and some stocks and sauces. Grinding the peppercorns allows their flavor to be extracted faster for last-minute adjustments. Grinding also frees their aromatics to evaporate, so the most and freshest flavor comes from whole peppercorns ground directly into the preparation. Even whole peppercorns lose much of their aroma after a month in a grinder. Some cooks briefly toast them in a hot pan to enrich their aroma.

Pepper is best stored tightly sealed in the cold and dark. If exposed to light during storage, it loses its pungency because the light energy rearranges piperine to form a nearly tasteless molecule (isochavicine).

Pink Peppercorns Pink peppercorns are fruits of the Brazilian pepper tree, Schinus terebinthifolius, which was brought to the southern United States as an ornamental and has become an invasive pest. Its attractive pink fruits were first marketed as a kind of pepper in the 1980s. The tree is in the cashew and mango family, which also includes poison ivy and poison oak, and its brittle, peppercorn-sized fruits contain cardanol, an irritating phenolic compound that limits its usefulness in foods. Pink peppercorns have fresh, pine, citrus, and sweet aroma notes thanks to several terpenes. A close relative from Peru, S. molle, is also grown as an ornamental and is called the California pepper tree. Its fruits have a more resinous aroma (thanks to myrcene), with less irritant cardanol.

Sichuan Pepper, Sansho The Chinese spice known as Sichuan pepper and the Japanese sansho both offer a strange and interesting version of pungency. They come from two small trees in the citrus family sometimes called “prickly ash.” Sichuan pepper trees are Zanthoxylum simulans or Z. bungeanum, and sansho trees are Zanthoxylum piperitum. (Xanthoxylum is another spelling.) The spices are the small dried fruit rinds, which are aromatic with lemony citronellal and citronellol. The pungent compounds, the sanshools, are members of the same family as piperine from black pepper and capsaicin from chillis. But the sanshools aren’t simply pungent. They produce a strange, tingling, buzzing, numbing sensation that is something like the effect of carbonated drinks or of a mild electrical current (touching the terminals of a nine-volt battery to the tongue). Sanshools appear to act on several different kinds of nerve endings at once, induce sensitivity to touch and cold in nerves that are ordinarily nonsensitive, and so perhaps cause a kind of general neurological confusion.

The Chinese and Japanese versions of this spice are different. Chinese Sichuan peppercorns are always toasted, so their citrus affinities are overshadowed by browned, woody notes that go well with meats. Japanese sansho is distinctly lemony, and is used to mask or balance the fattiness of some fish and meats. These spices are almost always used as part of a mixture.

Sandalwood Sandalwood is more familiar in incense than in foods, but the roots and heartwood of the tree Santalum album are sometimes used in India to flavor sweets. Its aroma comes mainly from santalol, which has woody, floral, milky, musky qualities.

Star Anise Star anise is the strikingly star-shaped woody fruit of a tree in the magnolia family, Illicium verum, a native of South China and Indochina. Its anise flavor comes from the same phenolic chemical, anethole, that flavors the entirely unrelated European anise (p. 414). The fruit itself, which may have six to eight chambers, carries more of the flavor than the seeds, and the unripe fruit is traditionally chewed as a breath sweetener. One traditional and important use of star anise is in Chinese meat dishes simmered in soy sauce; when onions are included, the result is the production of sulfur-phenolic aromatics that intensify the meatiness of the dish.

Tamarind Tamarind is the fibrous, sticky, aromatic, and intensely sour pulp that surrounds the seeds in pods of Tamarindus indica, a tree in the bean family native to Africa and Madagascar. The pulp can be extracted by soaking it in water for a few minutes, squeezing the fibrous mass, and straining off the flavored water; tamarind extract is also manufactured and sold as a thick paste. The pulp is about 20% acids, mainly tartaric, 35–50% sugars, and about 30% moisture, and has a complex, savory, roasted aroma thanks to browning reactions that take place on the tree as the pulp becomes concentrated in the hot sun. In much of Asia, tamarind is used to acidify and flavor sweet-sour preserves, sauces, soups, and drinks. Tamarind is also popular in the Middle East, and it’s one of the defining ingredients in Worcestershire sauce.

Turmeric Turmeric is the dried underground stem, or rhizome, of a herbaceous tropical plant in the ginger family, Curcuma longa. It appears to have been domesticated in prehistoric times in India, probably for its deep yellow pigment (curcuma comes from the Sanskrit for “yellow”). Turmeric has long been used to color skin, clothing, and foods for ceremonies surrounding marriage and death. In the United States, the main use of turmeric is to provide color and nonpungent filler in prepared mustards. It’s also the major component of most prepared curry powders, making up 25–50% of their weight.

The major pigment in turmeric is a phenolic compound called curcumin, which turns out to be an excellent antioxidant. This may explain why turmeric is considered to have preservative properties; in India fish and other foods are often first dusted with it before cooking, and it goes into many prepared dishes. The color of curcumin is sensitive to pH. In acid conditions it’s yellow, while in alkaline conditions it turns orange-red.

To make the spice, turmeric rhizomes are steamed or boiled in slightly alkaline water to set the color and precook the abundant starch, then sun-dried. Turmeric is usually sold preground, though fresh and dried rhizomes can be found in ethnic markets. Turmeric has a woody, dry earth aroma (from mildly aromatic terpenes called turmerone and zingiberene), with slight bitterness and pungency.

Vanilla Vanilla is one of the most popular flavorings in the world. Among the spices it’s unique for the richness, depth, and persistence of its flavor. And it’s the second most costly, after saffron. So in fact most of the vanilla flavoring consumed in the world today is a synthetic imitation of the original spice.

True vanilla comes from the pod fruit, often called the “bean,” of a climbing orchid native to Central and northern South America. There are about 100 species in the tropical genus Vanilla. V. planifolia(or V. fragrans) was first cultivated by the Totonac Indians along the eastern coast of Mexico near Veracruz, perhaps as long as 1,000 years ago. They sent it north to the Aztecs, who flavored their chocolate drinks with it (p. 695). The first Europeans to taste vanilla were the Spanish, who gave it its name; vainilla is the Spanish diminutive for “sheath” or “husk” (from the Latin vagina). A 19th-century Belgian botanist, Charles Morren, figured out how to pollinate vanilla flowers by hand, and thus made it possible to produce the spice in regions that lacked the proper pollinating insects. And the French took the vine to the islands off the coast of southeast Africa that now supply much of the world: Madagascar, Réunion, and Comoros, which collectively produce what is called Bourbon vanilla.

Today, Indonesia and Madagascar are the world’s largest producers. It’s the attentive and extensive labor required to hand-pollinate the vanilla flowers and cure the pods, and the low production of the few regions that cultivate it, that make vanilla so expensive.

Vanilla’s rich flavor is the creation of three factors: the pod’s wealth of phenolic defensive compounds, preeminently vanillin; a good supply of sugars and amino acids to generate browning-reaction flavors; and the curing process. The plant stores most of its defensive aromatics in inert form by bonding them to a sugar molecule. The active defenses — and aromas — are released when damage to the pod brings the storage forms into contact with bond-breaking enzymes. The key to making good vanilla is thus deliberate damage to the pods, followed by a prolonged drying process that develops and concentrates the flavor, and prevents the pod from spoiling.

Making Vanilla The making of vanilla begins six to nine months after the orchid flowers have been pollinated, with green pods 6–10 inches/15–25 cm long that are just beginning to ripen. On the pod’s inner walls, thousands of tiny seeds are embedded in a complex mixture of sugars, fats, amino acids, and phenolic-sugar storage compounds. The enzymes that can liberate the aromatic phenolics from storage are concentrated closer to the outer walls. The first step in curing is to kill the pod so that it doesn’t use up its sugars and amino acids, and to damage the pod’s cells and allow the phenolic storage compounds to migrate to the liberating enzymes. Both of these goals are accomplished by briefly exposing the pods to high temperatures, either in the sun or in hot water or steam. The cell damage that this causes also allows the browning enzymes (polyphenoloxidases, p. 269) to cluster some phenolic compounds together into colored aggregates, so the pod color changes from green to brown.

Then follow several days during which the pods are alternately exposed to the sun until they’re almost too hot to handle, then wrapped in cloth to “sweat” with the residual heat. During this stage, the main flavor components of vanilla — vanillin and related phenolic molecules — are freed from their bondage to sugar molecules. The heat and sunlight also evaporate some of the pod moisture, discourage microbial growth on the humid surface, and generate pigments and complex aromas via browning reactions between sugars and amino acids (p.778). It takes 3 to 5 pounds of fresh pods to produce 1 pound of cured beans.

Pods of the vanilla orchid. The fresh pod contains thousands of tiny seeds embedded in a sticky resin of sugars, amino acids, and a storage form of the main vanilla aroma compound, vanillin. The process of drying and curing the pod frees the vanillin and creates additional aroma molecules.

In the last stage of vanilla processing, the pods are straightened and smoothed by hand, dried for several weeks, then “aged,” or stored for some time to develop flavor further (flavor compounds react with oxygen, some heat-resistant enzymes, and each other to form fruity esters and other new notes). In Madagascar, vanilla curing takes 35–40 days, while the Mexican process lasts several months.

The Flavors of Vanilla The cured pod is about 20% water by weight, 20% fiber, 25% sugars, 15% fat, and the remainder amino acids, phenolic compounds, other flavors, and brown pigments. The sugars provide sweetness, free amino acids provide some savoriness, fat richness, and tannins some astringency. The aroma of natural vanilla is complex. More than 200 different volatile compounds have been found in vanilla beans. The principal one, the phenolic compound vanillin, does suggest vanilla on its own, but without the whole spice’s richness. Some of the other important vanilla volatiles contribute flavor notes described as woody, floral, green-leaf, tobacco, dried-fruit, clove-like, honey-like, caramel, smoky, earthy, and buttery.

Kinds of Vanilla The different vanilla-producing regions produce beans with broadly different flavors. Bourbon vanilla from Madagascar and neighboring islands is generally considered to be the finest, with the richest, most balanced flavor. Indonesian beans seem lighter, with less vanillin, and sometimes smoky qualities. Mexican beans contain about half the vanillin of Bourbon beans, and have distinctive fruity and winy aromas. Rare Tahitian vanilla beans — from a different species, V. tahitensis, also have much less vanillin than Bourbon beans, but carry unique flowery and perfumed notes.

Vanilla Extracts and Flavorings Vanilla extracts are made by chopping whole vanilla beans and repeatedly passing a mixture of alcohol and water over them for several days, then aging the extract to develop a more complex, full flavor. Vanillin and the other flavor components are more soluble in alcohol than water, so the higher the flavor content desired in the extract, the higher the proportion of alcohol necessary to carry it.

Artificial vanilla flavoring contains synthetic vanillin made from various industrial by-products, especially wood lignin, and doesn’t have the full, complex, subtle flavor of whole vanilla beans or their extracts. The demand for vanilla flavoring far exceeds the available crop, and natural vanillin costs about 100 times more than synthetic. About 90% of the vanilla flavoring consumed in the United States is artificial; in France, about 50%.

Cooking with Vanilla Vanilla is used mainly in sweet foods. Almost half of the vanilla flavoring consumed in the United States goes into ice cream, and much of the rest into soft drinks and chocolate. But it also works in savory dishes: lobster and pork are popular examples. Added with a light touch, vanilla can contribute a sense of depth, warmth, roundness, and persistence to almost any food.

The flavor of the whole vanilla bean resides in two different parts of the bean: the sticky, resinous material in which the tiny seeds are embedded, and the fibrous pod wall. The first is easily scraped out of the bean and dispersed in a preparation, while the pod itself must be soaked for some time in order to extract its flavor. Because the volatiles are generally more soluble in fat than in water, the cook can extract more flavor if the extraction liquid includes either alcohol or fat. Prepared vanilla extracts can be dispersed throughout a dish instantly, and are usually best added toward the end of cooking; any period of time spent at a high temperature causes aroma loss.

Tea and Coffee

Tea and coffee are the most widely consumed drinks in the world, and their popularity stems from the same source as that of herbs and spices: the plant materials they’re made from are crammed with chemical defenses that we have learned to dilute, modify, and love. Tea leaves and coffee beans have one defense in common, and that’s caffeine, a bitter alkaloid that has significant effects on our bodies. And they both contain large doses of phenolic compounds. However, they’re very different materials. Coffee begins as a seed, a storehouse of protein, carbohydrate, and oil, and is the creation of high heat, a robust epitome of roasted foods and flavors. Tea begins as a new, actively growing leaf, rich in enzymes, and is the delicate creation of those enzymes, carefully captured and preserved by minimal heat and drying. Coffee and tea thus offer two very different experiences of botanical inventiveness and human art.

Caffeine

Caffeine is the most widely consumed behavior-modifying chemical in the world. It is an alkaloid (p. 238) that interferes with a particular signaling system used by many different cells, and therefore has several different effects on the human body. Above all, caffeine stimulates the central nervous system, relieves drowsiness and fatigue, and quickens reaction times. It also increases energy production in muscles and so their capacity for work. It’s said to improve mood and mental performance, though recent studies suggest that these may be the result of relieving the initial symptoms of overnight caffeine withdrawal! Less desirably, in high doses it causes restlessness, nervousness, and insomnia. It has complex effects on the heart and arteries, and can produce an abnormally fast heartbeat. There is some evidence that caffeine speeds the loss of calcium from bone, so habitual consumption may contribute to osteoporosis.

Caffeine reaches its maximum levels in the blood between 15 minutes and two hours after consumption, and its levels are reduced by half within three to seven hours. Its effects are more noticeable in people who don’t normally consume it. Withdrawal symptoms can be unpleasant, but usually disappear within three days of abstaining.

A chemical relative of caffeine called theophylline is found in tea and is in some respects more potent than caffeine, but tea contains only trace amounts. Though coffee beans are 1–2% caffeine and tea leaves 2–3%, brewed coffee contains more caffeine than brewed tea because a larger weight of coffee is extracted per cup (8–10 grams, vs. 2–5 grams for tea).

Tea, Coffee, and Health

Not so many years ago, both coffee and tea were suspected of contributing to various diseases, including cancers, so they were among the many pleasures to feel guilty about. No longer! Coffee is now recognized as the major source of antioxidant compounds in the American diet (medium roasts have the highest antioxidant activity). Black and especially green teas are also rich in antioxidant and other protective phenolic compounds that appear to reduce damage to arteries and cancer risk.

Certain kinds of brewed coffee do turn out to have an undesirable effect on blood cholesterol levels. Two lipid (fat-like) substances, cafestol and kahweol, raise those levels, though they only get into the coffee when the brewing technique doesn’t filter them out. Boiled, plunger-pot, and espresso coffees contain them. The significance of this effect isn’t known and may well be small, since the cholesterol raisers are accompanied by a large dose of substances that protect the cholesterol from oxidation and causing damage (p. 255).

Water For Making Tea
and Coffee

Brewed tea and coffee are 95–98% water, so their quality is strongly influenced by the quality of the water used to make them. The off-flavors and disinfectant chlorine compounds of most tap waters are largely driven off by boiling. Very hard water, high in calcium and magnesium carbonates, has several undesirable effects: in coffee, these minerals slow flavor extraction, cloud the brew, clog the pipes in espresso machines and reduce the fine espresso foam; in tea, they cause the formation of a surface scum made up of precipitated calcium carbonate and phenolic aggregates. Softened water overextracts both coffee and tea and gives a salty flavor. And very pure distilled water gives a brew best described as flat, with a missing dimension of flavor.

The ideal water has a moderate mineral content, and a pH that is close to neutral, so that the final brew will have a moderately acid pH of around 5, just right to support and balance the other flavors. Some bottled spring waters are suitable (Volvic is used in Hong Kong). Many municipal tap waters are intentionally made alkaline to reduce pipe corrosion, and this can reduce the acidity and liveliness of both tea and dark-roasted coffee (light roasts contribute plenty of their own acid). Alkaline tap water can be corrected by adding tiny pinches of cream of tartar — tartaric acid — until it just begins to have a slightly tart taste.

Tea

Though it has lent its name to many other infusions, tea — from the Chinese word cha — is a drink prepared from the green leaves of a kind of camellia. Young tea leaves turn out to be as packed with interesting defensive chemicals as any spice. Beginning in southwest China around 2,000 years ago, people learned how to use physical pressure, mild heat, and time to coax a number of different flavors and colors from the tea leaf. Tea became a staple of the Chinese diet around 1000 CE. In 12th-century Japan, Buddhist monks who valued tea as an aid to long hours of study found that tea itself was worthy of their contemplation. They developed the formal tea ceremony, which remains remarkable for the attention it pays to the simplest of preparations, an infusion of leaves in water.

The History of Tea

Tea in China The tea tree, Camellia sinensis, is native to Southeast Asia and southern China, and its caffeine-rich, tender young leaves were probably chewed raw long before recorded history. The preparation of tea leaves for infusion in water evolved slowly. There’s evidence that by the 3rd century CE the leaves were boiled and then dried for later use, and that by the 8th century they were also stir-fried before drying. These techniques would give green or yellow-green leaves and infusions, and mild but bitter and astringent flavor. More strongly flavored and orange-red teas like modern oolongs were developed around the 17th century, probably beginning with the accidental observation that the leaves develop a distinctive aroma and color when they’re allowed to wilt or are pressed before being dried. It was around this time that China began to trade extensively with Europe and Russia, and the new, more complex style of tea conquered England, where consumption rose from 20,000 pounds in 1700 to 20 million in1800. The strong “black” tea that’s most familiar in the West today is a relatively recent invention, the result of intensive pressing; the Chinese developed it in the 1840s specifically for export to the West.

The Spread of Tea Production Until the late 19th century, all tea in world trade was China tea. But when China began to resist Britain’s practice of paying for its expensive tea habit with opium, the British intensified tea production in their own colonies, particularly India. For warm regions they cultivated an indigenous variety, Camellia sinensis var. assamica, or Assam tea, which has more phenolic compounds and caffeine than China tea and produces a stronger, darker black tea. They planted the hardier China types in the Himalayan foothills of Darjeeling and at high elevations in the south. India is now the world’s largest tea producer.

Today about three-quarters of the tea produced in the world is black tea. China and Japan still produce and drink more green tea than black.

The Tea Leaf and Its Transformation A fresh tea leaf tastes bitter and astringent, and not much else. This is a reflection of the fact that its major chemical component, even more abundant than its structural materials, is a host of bitter and astringent phenolic substances whose purpose is to make the leaf unattractive to animals. And its aromatic molecules are locked up in nonvolatile combinations with sugar molecules. Green tea retains many of the qualities of the fresh leaf. But the key to making oolong and black teas is encouraging the leaf’s own enzymes to transform these austere defensive materials into very different, delightful molecules.

How Tea Enzymes Create Flavor, Color, and Body The period of enzyme activity during tea-making has traditionally been called “fermentation,” but it doesn’t involve any significant microbial activity. In tea-making, “fermentation” means enzymatic transformation. It occurs when the tea maker presses the leaves to break open their cells, and then allows the leaves to sit for some time while the enzymes do their work.

There are two general kinds of enzymatic transformation in making tea. One is the liberation of a large range of aroma compounds, which in the intact leaf are bound up with sugars and so can’t escape into the air. When the cells are crushed, enzymes break the aroma-sugar complex apart. This liberation makes the aroma of oolong and black teas fuller and richer than the aroma of green teas.

The second transformation builds large molecules from small ones, and thereby modifies flavor, color, and body. The small molecules are the tea leaf’s abundant supply of three-ring phenolic compounds, which are astringent, bitter, and colorless. The leaf’s browning enzyme, polyphenoloxidase, uses oxygen from the air to join the small phenolic molecules together into larger complexes (p. 269). A combination of two phenolics gives a kind of molecule (theaflavin) that’s yellow to light copper in color, less bitter but still astringent. Complexes of from three to ten of the original phenolics are orange-red and less astringent (thearubigens). Even larger complexes are brown and not astringent at all. The more the tea leaves are pressed, and the longer they’re allowed to sit before the enzymes are killed by heating, the less bitter and astringent and the more colored they become. In oolong teas, about half of the small phenolics have been transformed; in black teas, about 85%.

The red and brown phenolic complexes — and another complex, between double-ring molecules of caffeine and the theaflavins — lend body to brewed tea, because they’re large enough to obstruct each other and slow the movement of the water.

The evolution of tea taste. The fresh tea leaf contains rich stores of simple phenolic compounds (catechin, left) that are colorless and bitter but not astringent. When the tea leaf is bruised or rolled, leaf enzymes and oxygen combine the simple compounds into larger ones with different colors and tastes. Brief enzyme action produces a yellowish compound(theaflavin, center) that is both very bitter and astringent. More extensive enzyme action produces a compound(theaflavin digallate, right)that is moderately bitter and astringent. As the phenolic molecules get larger, they get progressively darker and milder.

Making Tea

The Tea Plant and Its Leaves The best tea is made from the plant’s small young shoots and unopened leaf buds, which are the most tender and vulnerable and contain the highest concentrations of chemical defenses and related enzymes. The choice “pluck” is the terminal bud and two adjacent leaves. Most tea is now harvested by machine, and therefore contains a large proportion of older and less flavorful leaves.

Tea Manufacturing The production of tea involves several different steps, some standard and some optional.

• The newly harvested leaves may be allowed to “wither,” or sit and wilt for minutes or hours. Withering causes them to shift their metabolism in ways that change their flavor, and to become physically more fragile. The longer the withering, the deeper the flavor and color of the leaves and the brew they make.
• The leaves are almost always “rolled,” or pressed to break down the tissue structure and release the cell fluids. If the leaves are rolled while they’re still raw, this allows the leaf enzymes and oxygen to transform the cell fluids and generate additional flavor, color, and body.
• The leaves may be heated to inactivate their enzymes and stop the enzymatic production of flavor and color. High dry heat will also generate flavor.
• The leaves are heated to dry them out and preserve them for long keeping.
• The dry leaves are sieved and graded by piece size, which ranges from whole leaves to “dust.” The smaller the piece, the faster the extraction of color and flavor.

Major Tea Styles The Chinese developed a half-dozen different styles of tea. Three of them account for most of the tea consumed in the world.

Green Tea Green tea preserves some of the original qualities of the fresh leaf, while heightening them and rounding them out. It’s made by cooking the fresh or briefly withered leaves to inactivate their enzymes, then pressing them to release their moisture, and drying them in hot air or on a hot pan. In China, the cooking is done on a hot pan, and this “pan-firing” produces aroma molecules characteristic of roasted foods (pyrazines, pyrroles) and a yellow-green infusion. In Japan, the cooking is done with steam, which preserves more of the grassy flavor and green color in both leaf and tea.

Oolong Tea Oolong tea is made by allowing some modest enzyme transformation of leaf juices. The leaves are withered until they become significantly wilted and weakened. Then they are lightly agitated to bruise the leaf edges, allowed to rest for a few hours until enzyme action has turned the bruised edges red, pan-fired at a high temperature, rolled, and finally dried gently, at temperatures just below 212ºF/ 100ºC. Oolong tea brews to a light amber color with a distinctive fruity aroma.

Tea. The choicest pluck consists of the bud tip and two youngest leaves of each branch of the tea bush.

Making Green, Oolong, and Black Teas

Black Tea Black tea is made by allowing a profound enzymatic transformation of the leaf fluids. The leaves are withered for hours, rolled repeatedly for as much as an hour, then are allowed to rest for between one and four hours, during which enzyme action turns them a coppery brown and causes them to emit the aroma of apples. Finally, the leaves are air-dried at temperatures around 100ºC, and become quite dark.

Tea Flavor The taste of tea, a lively, mouthfilling quality, comes from several different sources. Tea is mildly acid and bitter and contains traces of salt. It’s also rich in a unique amino acid, theanine, which is itself sweet and savory, and partly breaks down during manufacturing to savory glutamic acid. Chinese green teas also contain synergizers of savoriness (GMP and IMP, p. 342). Finally, bitter caffeine and astringent phenolics bond to and take the edge off each other and produce the impression of a stimulating but not harsh body. This effect is especially important to the taste of black teas, in which it’s called “briskness.”

The aromas of different teas are strikingly different. In green teas, early application of heat prevents much enzyme activity in the leaves. Steam heat gives grassy and seaweed, shellfish notes to Japanese green teas (the sea notes from dimethyl sulfide), while pan-firing and drying produce moresavory, toasted notes in Chinese green teas. In oolong and black teas, enzyme activity liberates floral and fruity aroma molecules from their odorless storage forms, and produces a much richer, stronger aroma (more than 600 volatiles have been identified in black tea).

OPPOSITE: Making green, oolong, and black teas. Variations in processing produce very different colors and flavors from the same fresh leaves.

Cooks exploit tea flavor in a number of different preparations: marinades and cooking liquids, ices and ice creams, in steamed foods, and as a source of aromatic smoke (e.g., Chinese tea-smoked duck).

Keeping and Brewing Tea Well-made tea is fairly stable and can be stored for several months in an airtight container that is kept cool and dark. Tea quality does eventually deteriorate thanks to the effects of oxygen and some residual enzyme activity; aroma and briskness are lost, and the color of black tea infusions becomes less orange-red, more dull brown.

Teas are brewed in various ways in different parts of the world. In the West, a relatively small quantity of black tea leaves — a teaspoon per 6-oz cup/2–5 gm per 180 ml — is brewed once, for several minutes, then discarded. In Asia, a larger quantity of leaves of any tea — as much as a third the volume of the pot — is first rinsed with hot water, then infused briefly several times, with the second and third infusions offering more delicate, subtle flavor balances. The infusion time ranges from 15 seconds to 5 minutes, and depends on two factors. One is leaf size; small particles and their great surface area require less time for their contents to be extracted. The other is water temperature, which in turn varies depending on the kind of tea being brewed. Both oolong and black teas are infused in water close to the boil, and relatively briefly. Green tea is infused longer in much cooler water, 160–110ºF/70–45ºC, which limits extraction of its still abundant bitter and astringent phenolics, and minimizes damage to its chlorophyll pigment.

In a typical 3–5 minute infusion of black tea, about 40% of the leaf solids are extracted into the water. Caffeine is rapidly extracted, more than three quarters of the total in the first 30 seconds, while the larger phenolic complexes come out much more slowly.

Serving Tea Once tea is properly brewed, the liquid should be separated from the leaves immediately; otherwise extraction continues and the tea gets harsh. All kinds of tea are best drunk fresh; as they stand, their aroma dissipates, and their phenolic components react with dissolved oxygen and each other, changing the color and taste.

Tea is sometimes mixed with milk. When it is, the phenolic compounds immediately bind to the milk proteins, become unavailable to bind to our mouth surfaces and salivary proteins, and the taste becomes much less astringent. It’s best to add hot tea to warm milk, rather than vice versa; that way the milk is heated gradually and to a moderate temperature, so it’s less likely to curdle.

Lemon juice is sometimes added to tea to bolster its tartness and add the fresh citrus note to its aroma. It also lightens the color of brewed black tea by altering the structure of the red phenolic complexes (the complexes are weak acids themselves, and take up hydrogen ions from the lemon juice). Alkaline brewing water, conversely, tends to produce blood-red infusions from black tea, and can even make green tea red.

Iced Tea Iced tea is the most popular form of tea in the United States; it first caught on at the 1904 World’s Fair in steamy St. Louis. It’s made by brewing tea with about half-again as much dry tea per cup, to compensate for the later dilution by melting ice. The addition of ice to normally brewed tea tends to make the tea cloudy, due to the formation of particles of a complex between caffeine and theaflavin. The way to avoid this is to brew the initial tea at room or refrigerator temperature, over several hours. This technique extracts less caffeine and theaflavin than brewing in hot water, so the caffeine-theaflavin complexes don’t form in sufficient quantities to become visible in the chilled tea.

Coffee

Coffee trees are native to east Africa, and were probably first valued for their sweet cherry-like fruits and for their leaves, which could be made into a kind of tea. Even today an infusion of the dried fruit pulp is enjoyed in Yemen, where the seeds or “beans” were apparently first roasted, ground, and infused in the 14th century. Our word coffee comes from the Arabic qahwah, whose own origin is unclear. The coffee tree was taken to south India around 1600, from India to Java around 1700, and from Java (via Amsterdam and Paris) to the French Caribbean shortly thereafter. Today Brazil, Vietnam, and Colombia are the largest exporters of coffee; African countries contribute about a fifth of world production.

The History of Coffee Brewing The original version of brewed roasted coffee beans is the Arab version, which still thrives in the Middle East, Turkey, and Greece. The finely powdered beans are combined with water and sugar in an open pot, the mixture boiled until the pot foams, then settled and boiled to a foam once or twice more, and finally decanted into small cups. This is the coffee that found its way to Europe around 1600; it’s concentrated, includes some sediment, and has to be drunk right away or the sediment will increase the already considerable bitterness.

French Refinements The first Western modifications of coffee brewing date from around 1700, when French cooks isolated the solid beans within the liquid by enclosing the grounds in a cloth bag, and thus produced a clearer, less gritty brew. Around 1750, the French came up with the most important advance before espresso: the drip pot, in which hot water was poured onto a bed of grounds and allowed to pass through into a separate chamber. This invention did three things: it kept the temperature of the extracting water below the boil, it limited the contact time between water and ground coffee to a matter of a few minutes, and it produced a sedimentless brew that would keep for a while without getting stronger. The limits on brewing temperature and time meant a less complete extraction of the coffee. This reduced the bitterness and astringency, and allowed the other elements of coffee flavor more prominence, the tartness and aroma that were more appealing to European tastes.

Machine-Age Espresso The 19th century brought the invention of several new brewing methods. There was percolation, or allowing boiling water to rise in a central tube and irrigate a bed of ground coffee. There were plunger pots, which allowed the coffee brewer to steep the grounds, then push the grounds to the bottom with the plunger and pour the beverage off. But the biggest innovation in coffee brewing made its debut at the Paris Exhibition of 1855. That was Italian espresso, a word which means something made at the moment it’s ordered, rapidly, and for one customer. The way to make coffee fast is to force water through the grounds with high pressure. In the process, the pressure extracts a substantial amount of the coffee bean’s oil, and emulsifies it into tiny droplets that create a velvety texture and lingering flavor in the drink. Espresso is an expression of the power of the machine to force the most and the best from a traditional ingredient and make it into something new.

Coffee berries and seeds. Each red berry contains two seeds.

Coffee Beans

Arabica and Robusta Coffees Coffee beans are the seeds of two species of a tropical relative of the gardenia. Coffea arabica, a 15 ft/5 m tree that is native to the cool highlands of Ethiopia and the Sudan, produces what are known as “arabica” beans; and Coffea canephora, a larger tree native to hotter, more humid West Africa, produces “robusta” beans. About two-thirds of the beans in international trade are arabicas, which develop a more complex and balanced flavor than the robustas. They contain less caffeine (less than 1.5% by weight of the dry bean, vs. 2.5% for robustas), less phenolic material (6.5% vs. 10%), and more oil (16% vs. 10%) and sugar (7% vs. 3.5%). Robusta varieties didn’t become prominent until the end of the 19th century, when their disease resistance became important in Indonesia and elsewhere.

Dry and Wet Processing To prepare coffee beans, the ripe coffee berries are picked from the trees, and the seeds cleaned of the fruit pulp by one of two basic methods. In the dry method, the berries are left in the sun to dry, or first piled to ferment for a few days, then spread out in the sun. The fruit is then removed by machine. In the wet method, most of the pulp is rubbed from the seeds by machine, then the remainder is liquefied by a day or two of fermentation by microbes. The seeds are then washed in copious water, dried to about 10% moisture, and the adherent inner “parchment shell” removed by machine. Some sugars and minerals are leached out of wet-processed beans, so they tend to produce coffee with less body and more acidity than dry-processed beans. However they often have more aroma, and tend to be of more uniform quality.

Roasting Raw green coffee beans are as hard as unpopped popcorn, and about as tasty. Roasting transforms them into fragile, easily opened packages of flavor. Most people let the professionals take care of roasting, but it’s a fascinating (and smoky) experience to roast coffee at home, as cooks in many countries have long done and still do with equipment ranging from frying pans to popcorn poppers to special roasters.

Coffee beans are roasted to temperatures between 375 and 425ºF/190–220ºC; the process usually takes between 90 seconds and 15 minutes. As the bean temperature approaches the boiling point of water, the small amounts of moisture inside the cells turn into steam and puff the bean up to half again its original volume. Then at progressively higher temperatures, the proteins, sugars, phenolic materials, and other constituents begin to break into molecular fragments and react with each other, and develop the brown pigments and roasted aromas typical of the Maillard reactions (p. 778). At around 320ºF/160ºC, these reactions become self-sustaining, like a candle flame, and extreme molecular breakdown generates more water vapor and carbon dioxide gas, whose production rises sharply at 400ºF/200ºC. If the roasting continues, oil begins to escape from the damaged cells to the bean surface, where it provides a visible gloss.

When the beans have reached the desired degree of roast, the roaster cools the beans immediately with cold air or a water spray to quench the molecular breakdown. The result is a brown, brittle, spongelike bean, with the holes in the sponge filled with carbon dioxide.

The Development of Coffee Flavor The hotter the bean is roasted, the darker it gets, and its color is a good indicator of flavor balance. In the early stages of roasting, sugars are broken down into various acids (formic, acetic, lactic), which together with their own organic acids (citric, malic) give light-brown beans a pronounced tartness. As roasting proceeds, both the acids and astringent phenolic materials (chlorogenic acid) are destroyed, so acidity and astringency decline. However, bitterness increases because some of the browning-reaction products are bitter. And as the bean’s color becomes darker than medium brown, the distinctive aromas characteristic of prized beans become overwhelmed by more generic roasted flavors — or, conversely, the flavor deficiencies of second-rate beans become less obvious. Finally, as acids and tannins and soluble carbohydrates decline with dark roasting, so does the brew’s fullness of body: there’s less there to stimulate our tongue. Medium roasts give the fullest body.

Storing Coffee Once roasted, whole coffee beans keep reasonably well for a couple of weeks at room temperature, or a couple of months in the freezer, before becoming noticeably stale. One reason that whole beans keep as long as they do is that they’re filled with carbon dioxide, which helps exclude oxygen from the porous interior. Once the beans have been ground, room-temperature shelf life is only a few days.

Grinding Coffee The key to proper coffee grinding is obtaining a fairly consistent particle size that’s appropriate to the brewing method. The smaller the particle size, the greater the surface area of bean exposed to the water, and the faster its contents are extracted. Too great a range of particle sizes makes it hard to control the extraction during brewing. Small particles may be overextracted and large ones underextracted, and the resulting brew can be both bitter and weak. The common propellor grinder smashes all the bean pieces until the machine is stopped, no matter how small the pieces get, so coarse and medium grinds end up containing some fine powder. More expensive burr grinders allow small pieces to escape through grooves in the grinding surfaces, and give a more even particle size.

Brewing Coffee Brewing is the extraction into water of desirable substances from the coffee bean, in amounts that produce a balanced, pleasing drink. These substances include many aroma and taste compounds, as well as browning pigments that provide color (almost a third of the total extract) and cell-wall carbohydrates that provide body (also almost a third). The flavor, color, and body of the finished drink are determined by how much ground coffee is used for a given volume of water, and by what proportion of that coffee is extracted into the water. Inadequate extraction and a watery, acid brew are caused by grinding the beans too coarsely, so that flavor is left inside the particles, by too brief a contact time between coffee and water, or by too low a brewing temperature. Overextraction and a harsh, bitter brew result from an excessively fine grind, or long contact time, or high brewing temperature.

The ideal brewing temperature for any style of coffee is 190–200ºF/85–93ºC; anything higher extracts bitter compounds too quickly. For a standard cup of American coffee, the usual brewing time ranges from 1 to 3 minutes for a fine grind, to 6 to 8 minutes for a coarse grind.

Brewing Methods There are a number of different methods for brewing coffee. Most of them extract between 20 and 25% of the bean’s substance, and produce a cup containing somewhere between 1.3% and5.5% bean solids by weight. The facing chart places some of the major styles in relation to each other. Standard American filter-drip coffee is the lightest, and Italian espresso the strongest. The initial proportion of coffee to water is 1:15 for American, 1:5 for espresso. One clear lesson from the chart is that it’s always best to use too much coffee rather than too little: a strong but balanced cup can be diluted with hot water and remain balanced, but a weak cup can’t be improved. This principle can help avoid problems caused by the fact that cup and coffee scoop measures vary, and that scoops themselves are a very approximate measure (one 2-tablespoon/30-ml scoop may deliver anywhere from 8 to 12 gm coffee, depending on grind and packing).

Each brewing method has its drawbacks. Percolators operate at the boil and tend to overextract. Many automatic drip brewers aren’t able to deliver near-boiling water, so they brew for a long time to compensate, lose aroma, and extract some bitterness. Manual drip cones give little control over extraction time. The plunger pot leaves tiny suspended particles in the brew that keep releasing bitterness. The Italian stovetop moka pot operates above the boil, at around 230ºF/110ºC (and 1.5 atmospheres of pressure), and produces a somewhat harsh brew. Overnight extraction in cold water doesn’t obtain as many aromatic compounds from the ground coffee as the hot-water methods.

Espresso True espresso is made very quickly, in about 30 seconds. A piston or spring or electrical pump drives 200ºF/93ºC water through finely ground coffee at 9 atmospheres of pressure. (Inexpensive household machines rely on excessively hot steam, develop far less pressure, and take longer to brew, so the result is relatively thin and harsh.) The proportion of ground coffee is three to four times the amount used in unpressurized brewing, and deposits three to four times the concentration of coffee materials in the brew, creating a substantial, velvety body and intense flavor. These extracted materials include a relatively large amount of coffee oils, which the high pressure forces from the bean particles to form a creamy emulsion of tiny droplets, and which contribute to the slow, prolonged release of coffee flavor in the mouth, long after the last sip. Another unique feature of espresso is the crema, the remarkably stable, creamy foam that develops from the brew and covers its surface. It’s the product of carbon dioxide gas still trapped in the ground coffee, and the mixture of dissolved and suspended carbohydrates, proteins, phenolic materials, and large pigment aggregates, all of which bond in one way or another to each other and hold the bubble walls together. (For the milk foams often served with coffee, seep. 26.)

This chart summarizes the important features of some common ways of brewing coffee, and the kinds of brew they produce. The sta bility of a brew is determined by how many coffee particles remain in it; the more particles, the more bitterness and astringency continue to be extracted in the cup or pet

Methods of Brewing Coffee

Serving and Holding Coffee Freshly brewed coffee is best enjoyed immediately — its flavor is evanescent. The ideal drinking temperature is around 140ºF/ 60ºC, where a sip won’t scald the mouth, and the coffee’s full aroma comes out. Because it cools in the cup, coffee is usually held in the pot just below the brewing temperature. High heat accelerates chemical reactions and the escape of volatile molecules, so coffee flavor changes noticeably after less than an hour in the pot; it becomes more acid and less aromatic. Coffee is best kept hot by retaining its original heat in a preheated, insulated, closed container, not on a hot plate that constantly supplies excessive heat from below while heat and aroma escape above.

Coffee Flavor Coffee has one of the most complex flavors of all our foods. At its base is a mouth-filling balance of acidity, bitterness, and astringency. A third or less of the bitterness is due to easily extracted caffeine, the rest to more slowly extracted phenolic compounds and browning pigments. More than 800 aroma compounds have been identified, and they supply notes that are described as nutty, earthy, flowery, fruity, buttery, chocolate-like, cinnamon, tea, honeyed, caramel, bready, roasty, spicy, even winey and gamy. Robusta coffees, with their substantially higher content of phenolic substances than arabicas, develop a characteristic smoky, tarry aroma that is valued in dark roasts (they are also distinctly less acidic than arabicas). Milk and cream reduce the astringency of coffee by providing proteins that bind to the tannic phenolic compounds, but these liquids also bind aroma molecules and weaken the overall coffee flavor.

Decaffeinated Coffee Decaffeinated coffee was invented in Germany around 1908. It’s made by soaking green coffee beans with water to dissolve the caffeine, extracting the caffeine from the beans with a solvent (methylene chloride, ethyl acetate), and steaming the beans to evaporate off any remaining solvent. In the “Swiss” or “water” process, water is the only solvent used, the caffeine removed from the water by charcoal filters, and the other water-solubles are then added back to the beans. Some of the organic solvents used in other processes have been suspected of being health hazards even in the tiny traces left in the beans (around 1 part per million). The commonest, methylene chloride, is now thought to be safe. More recently, highly pressurized (“supercritical”) and nontoxic carbon dioxide has been used. Where ordinary brewed coffee may contain 60–180 milligrams caffeine per cup, decaffeinated coffee will contain 2–5 mg.

Instant Coffee Instant coffee became commercially practical in Switzerland just before World War II. It’s made by brewing ground coffee near the boil to obtain aroma, then a second time at 340ºF/170ºC and high pressure to maximize the extraction of pigments and body-producing carbohydrates. Water is removed from the two extracts by hot spray-drying or by freeze-drying, which retains more of the volatile aroma compounds and produces a fuller flavor. The two are then blended together and supplemented with aromas captured during the drying stage. Instant coffee crystals contain about 5% moisture, 20% brown pigments, 10% minerals, 7% complex carbohydrate, 8% sugars, 6% acids, and 4% caffeine. As an essentially dry concentrate, instant coffee is a valuable flavoring for baked goods, confections, and ice creams.

Wood Smoke
and Charred Wood

Neither wood nor the smoke it gives off is an herb or a spice, strictly speaking. Yet cooks and makers of alcoholic liquids often use burned or burning wood as flavoring agents — in barbecuing meats, in barrel-aging wines and spirits — and some of the flavors they supply are identical to spice flavors: vanilla’s vanillin, for example, and clove’s eugenol. That’s because wood is strengthened with masses of interlinked phenolic units, and high heat breaks these masses apart into smaller volatile phenolics (p. 390).

The Chemistry
of Burning Wood

Charred wood and smoke are products of the incomplete combustion of organic materials in the presence of limited oxygen and at the relatively low temperatures of ordinary burning (below 1,800ºF/1,000ºC). Complete combustion would produce only odorless water and carbon dioxide.

The Nature of Wood Wood consists of three primary materials: cellulose and hemicellulose, which form the framework and the filler of all plant cell walls, and lignin, a reinforcing material that binds neighboring cell walls together and gives wood its strength. Cellulose and hemicellulose are both aggregates of sugar molecules (pp. 265,266). Lignin is made of intricately inter-locked phenolic molecules — essentially rings of carbon atoms with various additional chemical groups attached — and is one of the most complex natural substances known. The higher the lignin content of a wood, the harder it is and the hotter it burns; its combustion releases 50% more heat than cellulose. Mesquite wood is well-known for its high-temperature fire, which it owes to its 64% lignin content (hickory, a common hardwood, is 18% lignin). Most wood also contains a small amount of protein, enough to support the browning reactions that generate typical roasted flavors (p. 778) at moderately hot temperatures. Evergreens such as pine, fir, and spruce also contain significant amounts of resin, a mixture of compounds related to fats that produce a harsh soot when burned.

How Burning Transforms Wood into Flavor Burning temperatures transform each of the wood components into a characteristic group of compounds (see box, p.449). The sugars in cellulose and hemicellulose break apart into many of the same molecules found in caramel, with sweet, fruity, flowery, bready aromas. And the interlocked phenolic rings of lignin break apart from each other into a host of smaller, volatile phenolics and other fragments, which have the specific aromas of vanilla and clove as well as a generic spiciness, sweetness, and pungency. Cooks get these volatiles into solid foods, usually meats and fish, by exposing the foods to the smoky vapors emitted by burning wood. Makers of wine and spirits store them in wood barrels whose interiors have been charred; the volatiles are trapped in and just below the barrels’ inner surface, and are slowly extracted by the liquid (p. 721).

The flavor that wood smoke imparts to food is determined by several factors. Above all there’s the wood. Oak, hickory, and the fruit-tree woods (cherry, apple, pear) produce characteristic and pleasing flavors thanks to their moderate, balanced quantities of the wood components. A second important factor is the combustion temperature, which is partly determined by the wood and its moisture content. Maximum flavor production takes place at relatively low, smoldering temperatures, between 570 and 750ºF/300–400ºC; at higher temperatures, the flavor molecules are themselves broken down into simpler harsh or flavorless molecules. High-lignin woods burn too hot unless their combustion is slowed by restricted airflow or a high moisture content. When smoking is done by throwing wood chips onto glowing charcoal, the wood chips should be pre-soaked in water so that they’ll cool the coals. Because it’s largely pure carbon, charcoal burns mostly smokelessly at temperatures approaching 1,800ºF/1,000ºC.

Though smoke helps stabilize the flavors of meats and fish, smoke flavor itself is unstable. The desirable phenolic compounds are especially reactive, and largely dissipate in a few weeks or months.

The Toxins in Wood Smoke: Preservatives and Carcinogens In the beginning, smoking was not just a way of giving foods an interesting flavor: it was a way of delaying their spoilage. Wood smoke contains many chemicals that slow the growth of microbes. Among them are formaldehyde, and acetic acid (vinegar) and other organic acids, thanks to which the pH of smoke is a very microbe-unfriendly 2.5. Many of the phenolic compounds in wood smoke are also antimicrobials, and phenol itself is a strong disinfectant. The phenolic compounds are also effective antioxidants, and slow the development of rancid flavors in smoked meats and fish.

In addition to antimicrobial compounds, smoke also contains antihuman compounds, substances that are harmful to our long-term health. Prominent among these are the polycyclic aromatic hydrocarbons, or PAHs, which are proven carcinogens and are formed from all of the wood components in increasing amounts as the temperature is raised. Hot-burning mesquite wood generates double the quantity that hickory wood does. The deposition of PAHs on meat can be minimized by limiting the fire temperature, keeping the meat as far as possible from the fire, and allowing free air circulation to carry soot and other PAH-containing particles away. Commercial smokers use air filters and temperature control for these purposes.

Liquid Smoke

Liquid smoke is essentially smoke-flavored water. Smoke consists of two phases: microscopic droplets that make it visible as a haze, and an invisible vapor. It turns out that much of the flavor and preservative materials are in the vapor, while the droplets are largely aggregates of tars, resins, and heavier phenolic materials, including the PAHs. PAHs are largely insoluble in water, while most of the flavor and preservative compounds do dissolve to some extent. This difference makes it possible to separate most of the PAHs from the vapors and dissolve the vapors in water. Cooks then use this liquid extract of smoke to flavor foods. Toxicological studies of liquid smoke have found that though it is full of biologically active compounds, the quantities normally used in foods are harmless. Those PAHs that do make it into liquid smoke tend to aggregate and sink over time, so it’s best not to shake bottles of liquid smoke before use. Leave the sediment at the bottom.

Wood Components and Smoke Flavors

Wood Component % of dry weight

Combustion Temperature

Combustion By-Products and Their Aromas

Cellulose (cell-wall frame, from glucose) 40–45%

540–610ºF 280–320ºC

Furans: sweet, bready, floral Lactones: coconut, peach Acetaldehyde: green apple

Hemicellulose (cell-wall filler, from mixed sugars) 20–35%

390–480ºF

Acetic acid: vinegar 200–250ºC Diacetyl: buttery

Lignin (cell-wall strengthener, from phenolic compounds) 20–40%

750ºF 400ºC

Guaiacol: smoky, spicy Vanillin: vanilla Phenol: pungent, smoky Isoeugenol: sweet, cloves Syringol: spicy, sausage-like